It was no surprise that substance abuse featured prominently in the late-night zingers last night — it was St. Patrick's Day, after all. What was unexpected was the number of pot jokes. The Tonight Show, The Daily Show,, and The Colbert Report all featured weed gags, which smacked of sacrilege on a day that is ostensibly drinking's birthday (Colbert managed to stay in character by claiming he'd found a five-leaf clover). On his show, David Letterman told a somewhat different story about expanding his horizons, and on Late Night With Jimmy Fallon the host debuted a mercifully old-fashioned drinking ballad. Watch our compilation to see what you missed.