Fag

Either a cancerous stick that one smokes (Cigarette)

or

An American term for a gay man

so:

Don't ask for a fag in the US, or tell anyone you're dying for a fag, or announce that you're sucking on a fag. This is suicide and despite your best efforts to convince the Rednecks otherwise, you will be forced to retreat to a hail of abuse, sticks, laughter or (if you meet dogface) flying lead hurled from a 12 gauge Remington.

Also...

To Fag (v): A junior student once used as an 'unpaid' servant by a senior student at the great universities in the UK. Although in today's world innocently asking someone to be your fag could result in your teeth going down your throat!

Find out more in the Dictionary