What is the problem, difficulty, etc?: What's with this guy? All I did was say hello
What is the explanation? why is this?: What's with the free food? Explain
[late 1930s+; fr Yiddish vos iz mit, ''what is with'']
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with what's with
Also,what's up with;what gives with. What is going on with; tell me about or explain it. For example, What's with all the food they're giving away? or What's up with Lee these days? or What gives with Jack? Why is he so glum? This idiom is also sometimes used as a substitute for how are you or what's wrong, as in Hi, Pam, what's with you? or What gives with you—why are you yelling?
[ ; c. 1940