The Half-Life 2 engine's modability has made it the king for user created video content that delivers over-the-top humor.

In celebration of the game's 13 year anniversary, below are eight of the funniest and most popular videos made in the Source engine.

The Idiots Of Garry's Mod 

As the original viral Garry's Mod series, The Idiots of Garry's Mod is an important one. Creator Djy1991 pioneered the quick scene to scene satirical machinima style that many other content creators would follow. Little did he know that it was just the beginning.

The Gmod Idiot Box

DasBoSchitt's The Gmod Idiot Box followed in the footsteps of Djy1991's two popular works, using the same format with even greater success. To-date he has released 14 episodes that have upward of 10 million views. Below are the two most popular of the bunch, and my personal favorites out of everything listed in this article.

Got High

Afroman's "Because I Got High" got some love in a 2007 machinima featuring Counter-Strike: Source. This is probably the best music video ever made.

Who's Cooking Tonight?

This scene uses Left 4 Dead characters and their voice dialog to make for great funnies. It would go viral in the Left 4 Dead community during 2012, reigniting interest for Garry's Mod machinima videos.

Scout's Caps

Diztah published Scout's Caps in 2012, which capitalized on Team Fortress 2's popularity with well-executed meme references and notably great animations. It currently stands as the most popular Team Fortress 2 machinima ever made.

Gravity Fails

Eltorro64Rus hit the jackpot with his 2014 hit titled "Gravity Fails". The video is set in the Team Fortress 2 universe with crazy interactions between its most popular characters.

The Toys Escape

With over 40 million views, there is no more popular Garry's Mod video than The Toys Escape. Made by none other than the famous VanossGaming, it shows a few players messing around in a Toy Story style map. 

Happy 13th birthday to Half-Life 2!