It's Always Sunny in Philadelphia: Season 6, Episode 3

6 - 3: The Gang Buys a Boat

Mac, Charlie and Dennis buy a boat to "throw some P. Diddy-style parties," as Mac puts it, and, Charlie insists, to harvest shrimp (or barnacles). They end up with a run-down houseboat, the Drowning Sailor, and Mac and Dennis order Dee (who didn't invest in it) to clean it up. Frank, sledgehammer in hand, offers to help.