Hmm.. Do you go to South Park
Speaking as an English
person, I have never
heard the phrase Blowing a fag
Smoking a fag or Having a fag are in frequent use - as in the UK a fag is universally understood to be a cigarette.
The colloquial (and usually derogatory) term for a gay person is generally poof, queer, fairy, queen, or one of many other (more offensive) slang terms.
As the old song goes; "You say Tomato.."