What is this crud in my navel?

So I´m down at the swimming pool and I peel off my T (if you just joined us, yes, I still enjoy a good swim every day and what I do, right, is I lurk in the gutters around the edge of the pool, you know, the ones where the water disappears into the filters, okay so, I hang there and then when someone swims past i sort of like, totally dart out and try and nip their heels, anyway, it is totally freaking hilarious to me) and as I peel off my T one of the other dudes, he goes, ´ewwwwww, gross WHAT IS THAT CRUD IN YOUR NAVEL MAN?´ and I look down and yeah, okay, there is this string of grey fluff hanging out of my navel and as I pull it out it just TOTALLY keeps on coming until I have this 1 inch string of crud hanging out my navel and I´m like, ´that really is gross´ and they´re all, ´no way are you getting in the pool with that navel dude´ and they chase me out of the swimming pool and I have to go home and eat like a million pringles and dwell on it. There are some radically big questions that need answering here.

I never used to have navel crud. At what age do you start to develop navel crud? And why? Like how come last year I never used to get navel crud and now I do, and also, how does it form, I mean is it crud from your tees or is it some sort of alien life form that like seeks out the warmth and humidity of navels and then in the middle of the night or when you are like otherwise occupied loving up the lady rat, does it kind of creep in there and make a nest?

I mean, you know. I was so totally completely yukked out that I shaved my entire body in order to like, totally prevent any chance that my own fur is crudding up my navel. I take this sort of thing like, serious.