It's more a military phrase. A formation of soldiers would be allowed to smoke cigarettes if they had any. "Smoke them if you've got them". Tim said it right.

The phrase "Smoke 'em if You Got 'em" or "Smoke if You Got 'em" is slang for "do what you want, if you have the means". The first phrase was popular in the military during World War II, meaning to take a break. Officers would say "Smoke 'em if you got 'em", allowing the soldiers to take a break and smoke their cigarettes source: wikipedia

Smoke 'em if you got 'em