1. When a person's outerwear is wedged between the buttocks giving the impression that the buttocks themselves are attempting to eat the garment.
2. Extreme version of a wedgie.
3. Often the result of wearing ill fitting undergarments, a thong or going commando.
When I wore a thong, my shorts kept trying to crawl into my butt crack too. It looked like I had a severe case of hungrius assius.