I once made an exploding cigar for Einstein, but he smoked pipes. He regifted it to Feyman, who sensed a practical joke in the works but was a good sport and lit up anyway. Pauli snatched it from his mouth and threw it out the window, where Oppenheimer was chatting with General Groves. It landed on Groves's hat. The quick-thinking Oppie grabbed the hat off his head – a severe breach of protocol regardless of the situation – and was just about to stomp on when it POPPED, ruining the hat. They docked my pay for that, which caused a bitter row with Laura on the home front, let me tell you.
Those were crazy times.