Japanese Girlfriend Breakup

Hey, listen up, you absolute walnut. This joke is dark. Real dark. It's playing on the tragic history of Japan during World War II, specifically the atomic bombings of Hiroshima and Nagasaki. The punchline suggests that just like those devastating events, you gotta 'drop the bomb' twice—meaning you have to break up with her more than once—before a Japanese girlfriend understands it's over. Get it? It's funny because it's awful. And you, my friend, probably still don't.