I worked with a guy that was a SFX guy for the old Walker TV series. Talking about some fun stories. He showed me a few "near misses" where the explosion was "slightly" larger than anticipated, and if you know where/when to look, you see the SFX team running for their lives in footage that made it into the edit. None of the guys I've worked with come close to the Danny McBride character in Tropic Thunder though.