Gyarados

Gyarados is a large, blue, dragon-like animal hailing from the hit Pokemon gaming series. Recognizable by its serpentine body and constantly opened mouth, Gyarados is a popular choice among male players for its fierce and intimidatding looks.
Gyarados evolves from Magikarp, conversely the weakest of all Pokemon by far. Evolving a Magikarp into a Gyarados is highly worth it, however, as a well-raised one can effectively rape the shit out of many other Pokemon.

The accidental yet embarrassing act of blowing water out of a bong through the slider, soaking the Marijuana. It gets its name because the action closely resembles the Pokemon Gyarados.
It often happens with first time bong users who forget they can't blow out the ash like they can with a bowl or pipe.

What happens to a penis when it comes into contact with poison ivy after taking a wizz in the woods.

The effect of someone or something getting infinitely better/more badass/awesome within a short space of time, similar to how a Magikarp can evolve from a horrifically weak pokemon into a Gyarados, which is very powerful.

When a person who originally is unattractive ages/hits puberty and is transformed into a sexy beast.
Originates from Pokemon, when a weak Magikarp evolves and becomes a powerful Gyarados.