Deciphering Boys: Gross Things

What is it about the Y chromosome that compels its owners to an eerie fascination with gross things? Like some kind of strange black hole, pictures like the one below seem to pull on a boy's mind and place him in a sort of hypnotic state. Transfixed gaze, slightly elevated heart rate, open-mouthed wonder at the hideousness of it, yet unable to pull himself away. Daniel opens up to this page of our "Ancient Egypt" book every time he looks at it. He asks about where the man's eyeballs are now and whether or not those are his original teeth. Now, I certainly find mummies and ancient Egypt to be quite spellbinding myself, but a five-second look at the mummy photo will suffice. The death and decay are not a pleasing sight.
Here are two more examples of the love of gross things amongst boys:

1. Nathan had a friend over recently and they were talking about snakes. (No, I do not put snakes in the gross category, in and of themselves.) His friend was saying, "You have to go on youtube and watch 'Snake regurgitates antelope'! It's so awesome!" The antelope is dead and all covered with slime, which I guess must have been part of the excitement. That was the gist of it anyway, and of course, Nathan did ask me to see it later that day. (If you must watch it yourself, follow this clue.)
2. (This is literally "#2", just so you're forewarned.) Nathan came out of the bathroom the other day and said to me, with a huge smile on his face, "I weighed myself and it was 66. Then I went #2 and then I weighed myself and it was 65.5. Cool, hu?"

Note: I know I said I would refrain from toilet topics for awhile, but at the time I said that, I really hadn't given enough thought to how much of my life seems to involve the bathroom.

So what is the answer to this mystery of why boys have such an affinity for gross things? Does it make them feel more manly if they like them? Do they truly just relish the look of those things? My personal opinion is that if they convince themselves (and other people) that they love those gross things, then they won't feel so scared of them. Find it funny or awesome and it loses some of its horror. Maybe I'll have to test this hypothesis somehow...