Smoking a fag in the UK means to smoke a cigarette.
Smoking a fag in the USA means to kill a homosexual.
Cultural Meanings
Explanation
Explain Bear
Listen up, smooth-brain. In Britain, a "fag" is just a smoke. In the States, "smoking" someone means you're blasting them with a lead pipe. It's a linguistic trap for tourists. You're probably the type who can't even read a map, so pay attention.