An ugly transsexual that you don't want to have sex with or a transsexual that is making a scene around you that kills the joy that you were experiencing during your night out. It comes from the words transsexual and grenade.
Dude... did you see Vinnie at the club last night he was dancing with this crazy ass trenade, it was messed up when he kissed it... and then we told him outside... and he threwup when he relized what he did. That trenade over there is super gross. Watch out at Crowbar... there are fuckin trenades all over.