An Assclam is the walk a person does when they have to go to the bathroom. Holding their asscheeks tightly together, like a clam. Sometimes snapping them together quickly to avoid smudge marks. An insult to a person whom walks, or acts funny.
Hey look Chrissy! That guy is an ass clam,I hope he shits himself real good.
Look at his ass clam, he must have to pinch one off, you know sally?
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?"