If I play a game a second time, I'll use a silly name. Like the second time I played Persona 3, I named the guy "Studman Studman" because it was funny seeing Mitsuru say stuff like "hey Studman, do you feel like going to Tartarus tonight?" Or in FF9, I renamed Amarant to Lips so he'd say "some call me The Flaming Lips." (Yes I am secretly 12 years old:P And The Flaming Lips are an awesome band.)
I've named characters "I say" so that all the characters who talk to them sound like Foghorn Leghorn.