You are hereTF2: Jarate!
Valve... you have just BLOWN MY MIND. The Sniper has retaken over the update page (which has now become /sniper_vs_spy) and along with an achievement list, he's gotten his third unlockable. You remember Meet the Sniper? Remember the Sniper's jars of wee? Ever thought it would be freakin' hilarious if you could throw those at someone? Then you're in luck! Jarate!
Jarate (Jar-based karate) is a jar of piss that you can throw at people. Simple and not so sweet, yet with a multitude of uses. Enemies who get splashed on take 35% more damage, it'll short out a Spy's cloaking device and can extinguish fire effects on teammates (but is it worth it??).