Glasgow, Scotland origin, derogitary name given to one who is annoying, useless or just plain stupid. To compare one with such an ugly part of the male anatomy should be insult enough...
"Look you fuckin' bawbag, you are about as useful as a tit with no nipple."
complete and utter tool,usually bucky induced and wearing ned clobber
any mair o your pish ya bawbag and am gonnae ram ma fit up yer ring!