"baw" translates into english as ball. thus making the wordball bag but in the "weegie" tongue it is pronounced baw. and is the perfect insult to any one in any situation. "utter baw-bag"
"here you ya baw-bag!"
"i can't beleive you done that yer a totaly baw-bag"
"aw big jon? he's a total baw-bag"