I'm not sure it is a metaphor. It doesn't literally remove your footwear, but it doesn't do so metaphorically either. I think it's an imaginary cartoon situation, where you draw someone with one of those little bombs that look like bowling balls with a fuse sticking out, and when it goes off all your clothes are blown off. But that's not really a metaphor, it's comic exaggeration. I think Garaman is right, it's an idiom rather than a comparison with anything else that actually happens.