Some more ideas for signatures:
Bowser is like a bigger brother; big, pushes you around, and has bad breath to boot!
You suck and that's sad.
C'mon, do the Mario! *Does the splits by accident* Medic...
In life, there are gamers, readers, and the downright crazy.
Don't touch me, I'm hot!
Have you booted your computer today? *KICKS COMPUTER*
SMILE LIKE YOU MEAN IT! (Even though you don't. ;) )
I'm a cow. *flaps arms and barks uncontrolably*