Can I bum a fag?

exp.

Heard in Waterford

It means could I please borrow one of your cigarettes... bum meaning to borrow and fag meaning cigarette. Give us the butt off of that fag is a similar term.

In use

Jaysis boy, could I bum a fag? I haven't had a drag in yonks, I could do with a few puffs.

Posh English

Good heavens, old boy, might I borrow a cigarette? I have not enjoyed a draw in ages and could certainly use a few puffs.