Ex-Playboy Playmate Colleen Shannon -- Orange Is the New Nude ... Sentenced to Prison for BF Smuggling

Ex-Playboy Playmate Colleen Shannon better look good in orange -- she's been sentenced to 4 months behind bars for smuggling a foreigner into the country ... TMZ has learned.

We broke the story ... Shannon was arrested in Aug. 2012 for trying to sneak her boyfriend, Robert Skojo, across the Canadian border. She was charged with transporting an alien.

Shannon, who was Playboy's 50th anniversary centerfold, must pay a $5,000 fine ... in addition to the prison stint.