Sgiwsiwch fi, fwyn gyfeillion, am fod 'mbach yn gwrs. Diffiniad The Urban Dictionary:- 1. The head of the penis, being vaguely bell shaped. Like a mushroom head. 2. A complete idiot. When you are drunk, you dance like a bellend. Yr ail ystyr sydd dan sylw yma. Ai 'coc oen' fyddai'r cyfieithiad gorau? Diolch Anna Ye who opt for cut'n'paste Tread with care and not in haste!