Quote from Ross in The One with Ross's Sandwich
Ross: Phoebe, Phoebe. Your note? Amazing. Not only did no one touch my sandwich but people at work are actually afraid of me. Yeah, a guy called me "Mental." "Mental Geller." I've always wanted a cool nickname like that. Monica: Yeah, the best you got in high school was "Wet Pants Geller." Ross: It was the water fountain, okay?!