This is reference to John Belushi in Animal House. When he was in the middle of an inspirational speech, he asked the rhetorical question: "Did we give up when the Germans bombed Pearl Harbor?" When questioned, Otter said: "He's on a roll, just let him go".
(When someone attempts to interrupt you) "Hey, just let me finish, I'm having a 'German Pearl Harbor Moment'"
by MNMustangfreak September 13, 2009