Warcraft 3 has many easter eggs but the most noticable are it's quotes. If you click a hero/unit too long then you'll get an easter egg where the hero/unit will get annoyed and will trigger a funny quote, usually a movie referance.
To start, i'll begin with the classic:
Ahh yes the greatest race in Warcraft lore, the Nathrezim. These guys are basically the consigiliere's for the Burning Legion (Kil'jaeden being the godfather). They host secret meetings and fuck things up, usually for their own amusement though their actions usually harness subtle intentions. When they're not in conferance, they often spend their time delegating and feasting on mortal souls. Dreadlords can be friend or foe, it all depends on the circumstance. Nevertheless, you should never trust a Dreadlord, they will gladly eviscerate you after you've served your purpose.
The Dreadlord is made fun of in the easter egg by being refered to as a "Druglord" and considering his shifty nature, it wouldn't be surprising. They also point fun at the fact that he's always walking even though he has wings. Apparrently the Dreadlords all have cellphones, possibly to converse with their bretheren or in this case darkness itself.
The Pit Lord is the complete opposite of the Dreadlord but still manages to be awesome. Unlike the Dreadlords who would rather use their minions to do their dirty work, Pit Lords love getting down and dirty and you can tell, they're giant pig demons for christ sake, they practically love rolling in muck or in this case, blood. They are essentially the Burning Legion's equivelent of Death Knights and charge into battle with their minions, unlike Death Knights however, Pit Lords are far less forgiving and may kill their own minions for failing them and sometimes just for fun. Like Dreadlords they enjoy being decisive but they often fail at it, so much so that they are seen as a laughing stock amongst the Dreadlords.
The Pit Lord is mocked for his grotesque appearance, he is pretty much a demonic pig after all. He's also mocked for having some of the largest teeth in history
There is also a Fat Albert referance... guess why this is fitting and you win a point.
Ahh the Blademaster, the hero everyone hates to see and for good reason, they steal your items, murder your workers and instagib your units with crit strike. Did i forget to mention that their primary move makes them invisible and move twice as fast!? Basically Blademasters are OP sons of bitches, they are the key to winning every game of Warcraft 3.
In lore, Blademasters are a rare sight, the only notable one being Grom Hellscream who unlike most Blademasters is far less disciplined.
The easter egg is filled with referances to commercials usually involving bladed products as he is all about hacking and slashing. This fits his character perfectly as his crit strike skill allows players to win by simply auto-attacking and the Blademaster does just that.
My god these guys are filled with easter eggs, try and guess all the referances. Mortar Teams are often mailed to the enemy team using the invisible spell or a zeppelin to destroy their town hall from behind. They're also used against Siege Tanks and Crypt Fiends. They attack by using massive mortar cannons which deal a lot of siege damage but as units they are pretty weak, they can also shoot flares to reveal an area of the map, very handy.
They have so many quotes it's difficult to tell what the main theme behind them was, many of them refer to their mortar cannon but others feel kinda off topic. Still very funny quotes though.
Acolytes are the Undead worker unit, they are humans who devoted themselves to Ner'zhul (the Lich King) and joined the cult of the damned to assist the Scourge's war efforts by summoning hideous constructs to produce more monsterous undead units. Some even offer their own lives to Ner'zhul as a tribute and become...
The acolyte's quotes are some of the funniest and mostly revolve around darkness. He also claims to know the secret to eternal happiness. I guess being evil in't all that bad after all. Sign me up!
The shade's quotes are mostly jokes about being ethereal. If these guys don't convince you to join the scourge, nothing wi... oh wait
Kel'thuzad is Arthas' ever lovable suave side kick. He leads the cult of the damned but is a mere pawn of the scourge. Still he is a highly intellegent necromancer who is talented in many forms of magic. He is essentially the scourge's answer to Stephen Hawking.
His quotes represent his leadership over the cult of the damned and how he is essentially the chief recruiter for the scourge.
Varimathras is one of the three Dreadlord insurgents and is a badass motherfucker. Easily my favourite playable character in the campaign. Unlike his brothers, Balnazzar and Detheroc who use possession and mind control to subjugate their targets, Varimathras has none of those powers but has a silver tongue to match. This guy can talk his way through anything and is very persistant at feigning loyalty. He tends to play it cool for the most part and would go to any lengths to save himself from suspicion.
Being a dreadlord, Varimathras is well informed and proves a rather useful ally to Sylvanas...temporarily of course (if you read Ashbringer you'd know). Humans are basically toys for his own amusement but they can also be quite productive in the right situations.
His quotes mostly refer to him being "always on the winning side" due to his silver tongue and will string the player along trying to fool them into joining his side.
Being a horseman, the Death Knights quotes revolve mostly around the four horsemen of the apocalypse among other things.
Death Knights are fallen warriors (usually nobles) who have fallen in battle to the scourge but their noble heritage lives on in death as they have become the lich king's loyal death knights. These guys are natural born leaders and are often leading scourge forces into battle (unlike Dreadlords who would rather sit back and watch, occasionally toying with their opponents). I never understood how they all get their horses though but somehow every Death Knight is commissioned with one.
The Necromancers quotes mostly refer to reanimation. As they are human and usually spend time amongst rotting corpses, they become obsessed with the sensation of becomming reanimated and it is their goal to die and become liches once they have served their purpose as a human. As humans, necromancers serve as leaders amongst the acolytes and are usually sent to scout the populace to convert people to their cause. Afterwards they become liches and wield greater power as an undead.
The lich is a necromancer who sacrificed himself for Ner'zhul. Unlike shades, they are not completely ethereal, probably due to their necromantic talents which are used to create themselves a new body from their corpse, possibly other corpses. Liches wield great power, possibly gifted by ner'zhul. The power of frost and the power to sacrifice minions to increase their own powers. Liches suck in the power of death to create more and more death... if you know what i mean.
Their quotes represent their lack of body parts. As undead, they weren't able to salvage all of their body parts so they have to improvise, even so far as to attempting to impress the ladies with their new look.
Some Night Elves chose not to be tree-hugging hippies. These night elves chose the path of arcane and fel magic and are also adept ad physical combat too. Armed with great magical power, they can be a force to be reckoned with that can even match the might of a demon. These are Demonhunters.
The Demonhunter quotes poke fun at their obsession for fel magic and their defiance towards Night Elf culture. One of their quotes is "i love green trees" backwards. It appears that the Demonhunter and the Dreadlord are aquainted despite being mortal enemies. They're both friends of darkness though.
When morphed, the demon hunter's voice is deeper than Keanu Reeves... or so it seems.
Despite his size, the Mountain King is a mighty warrior and he won't let anyone say otherwise. Mountain Kings are fearless and just as powerful as even the strongest of orc warriors. What they lack on size, they make up for in stregnth and believe me, this guy's got a lot of muscle. He is also an avid drinker and appears to be british, much like my relatives.
Honestly this is what happens when you combine pretty much every single member of my family with TheDustinThomas. A legend is born.
Last but not least is the philosophical spirit walker. His quotes point fun of his overly philosophical views. Pretty much Mareg from Grandia 2.
Spirit walkers are tauren who follow the earth mother. They are able to become ethereal and commune with the spirits. Basically the Tauren equivelant of a Shaman, just replace elements with spirits.
In battle, they're handy to have as they can link your units together to spread out damage to prevent your units from being focus fired. they also ressurrect Tauren and dispel magic. Just one of these guys can make a huge differrence in battle.
And that's all, i hope you found these quotes as funny as i did. As for other easter eggs Warcraft 3 has... theres a lot, the entire ending credits is an easter egg in itself where they re-do the entire Warcraft 2 intro... with a twist. There's also the worlds largest panda and the secret tower defense level. There are even more but i won't go into them, there's just so many easter eggs in Warcraft 3.