Gravity Bomb, (or G-Bomb), Refers to when a person, usually male, goes to the toilet and drops a massive shit into the bowl. This 'massive shit' usually descends from the asshole as one massive, sphere-shaped, ball that explodes into the water with its own unique sound according to the manner in which the G-Bomber has pushed out his/her G-Bomb

When you're being horny (especially around friends) and as a result shame ensues.

taking a hard spill, fall or wreck