When Banner transforms into Hulk there's usually some shirt-shedding involved, as this video demonstrates. Watches, shoes, belts etc. are similarly ripped off. Yet Hulk always seems to be able to keep his shorts, no matter how much he expands.
Obviously, I can appreciate the pragmatic, out-of-universe reason why the comic creators and the film-makers wouldn't want a starkers Hulk running about. Is there any in-universe explanation for why Hulk rips everything apart from his shorts?
Answers from either the films or the comics are fine (though I confess I'm not at all familiar with the latter).