XKCD Isn't Bad - #1382 - ROCKET PACKS

Pretty much my only problem with this comic is that it wasn't immediately apparent that the lower legs were supposed to be burnt specifically. I got that they were injured, and the title made it obvious that they were injured because of the backpack, but it looked like the person had just smashed up his lower legs on touchdown.

If this had been a three-panel'er, with the first panel having the person flying fine, the second having him loosing control, and the third having him burning his shins lower legs (the captions would be where they are, the beginning and the end), that would have been better for expositing the joke.

All in all, though, it's just another brick in the wall, it was a pretty clever joke that I don't think has been done before, and I'd definitely give this one a passing grade if I gave letter grades.