Placing your hand on the front of your pants and making exaggerated masturbatory gestures (either for the purpose of achieving an orgasm or to show off).
1. Did you see those guys fronting at the cheerleader tryouts?
2. Several guys at the school dance formed a fronting conga line before the principal stepped in to stop it.
3. Hugh G. Rection was fronting for almost a minute in drama class before the teacher figured out what was going on.