Simple. Just list any of your favorite powerups from any game. Does not matter how old or little-known the game is...
I have another. Dog Mode (Rise of the Triad). It's a hilarious take on God Mode where you see through the viewpoint of a dog. Whenever you use your melee attack, a dog's paw lashes out and strikes the enemy. xD
Adrenaline Pill (Early Grand Theft Auto games) Everything go's into slow motion, all voices go super deep, and the most amusing, your punches turn super charged, and when you hit a old granny of a bridge, she goes flying to tim buck two XD