O man this is so embarrassing, but sometimes when I'm alone...
I fap.
Okay for real though. Sometimes I start up audacity and start recording random shit I say in different tones to practice my voice acting. And if I say anything I find hysterical I save it and send it to my friend to see if he wants it in his machinima. I can't do my lines if anyone else is around.
And heres some guilty pleasure music that I sometimes sing along to.
I forgot, I also sometimes air guitar to solos and air drum all the damn time.