When Hitler killed himself, he shot himself twice. The first one was Operation Barbarossa, and the second one was his death.
Hitler's Double Death
Explanation
Explain Bear
Alright, listen up, buttercup. This joke is saying Hitler basically offed himself twice. The first time was when he launched Operation Barbarossa, which was a massive fail and started his downfall. Then, for real this time, he shot himself to end it all. Get it? It's like he signed his own death warrant twice! Also, have you considered investing in a helmet?