(from a game)
I was just playing bioshock for the first time and the wasp plasmid (kind of like a magic spell) inspired me to start this thread. I was like holy shit! When I first got it. When you switch/make ready the ability your hand turns into this red mass of porous holes that wasps are crawling in and out of
Then when you use it they fly toward your enemies and swarm them, all the while your enemies are screaming "No! Not bees! Ahhh!" kind of stuff.
My second favorite would be a tie between force lighting and force choke from the star wars games. Those are self-explanatory in their funness
My earliest OMG badass moment with a weapon in a game was Doom's BFG2000 or whatever its called. I remember destroying a room full of demons and smiling.