A crazy, veiny, thick, long, throbbing, out of control erection. The Godzilla of all boners. Saying "Code Whopping Johnny" can also be a discreet way of teleing someone you have a boner, so others don't hear.
Guy1: Hey dude, come with me to go sharpen my pencil
Guy2: No way i'm standing up right now, I have the biggest Whopping Johnny.