It's Always Sunny in Philadelphia: Season 8, Episode 1

8 - 1: Pop-Pop: The Final Solution

Dennis and Dee's ailing grandfather Pop-Pop is wasting away in the hospital, and they have to decide whether or not to pull the plug. But things get complicated when The Gang learns of Pop-Pop's history as a Nazi, and Mac, Charlie and Frank set off in search of the old man's spoils from the war.