A playful or mocking shorthand for chalant (the rarely used opposite of nonchalant), used to describe someone acting overly concerned, dramatic, or doing too much. Often implies being sensitive, trying too hard, or caring way too deeply about something that doesn’t matter that much.
As an adjective:
“Bro was acting real chall when she didn’t text back in 5 minutes.”
As a verb (“challing” / “challing out”):
“Stop challing out, it’s not that deep.”
“Why you challing over a game?”
A combination of "what do you/what are you/what have you" or "whatcha" with "Y'all" to form a compound word used to ask what a group of people think, want, or do.
What'chall want from the store?
What'chall think of this?