Well, without a clearer photo it is really hard to tell. It is completely normal for there to be a strip of smegma (sperm plug) hanging out of a male's vent occasionally. You want them to shed this, and normally it comes out with a poo and the cham wipes it off onto a branch. Sometimes it gets hung up there, though. Smegma colors run from creamy white to light brown. So, it could be that. The only other alternative I know of would be an adult parasite of some kind.