the upper crack of the arse, usually visible when one's trousers are descending off the hip, which is readily accessible to the accumulation of lint and other undesirable particulate.
When I bent over to fix the sink, my wife informed me that my lint trap was highly visible, and that aside from the lint that I was packing, that I ought to reconsider going into the bathroom and wiping my ass another 7 times.
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.
FRIEND A: "Did you just take a stealthie of me?"
FRIEND B (turning phone around): "no I was just using snapchat's new filter, see?"