What’s with…?

When demanding an explanation for something we see

You can use this phrase in ………… language.

 Spoken
Informal

Example 1
“What’s with the new banner?”
“The boss thinks we need to freshen things up.”

Example 2
“Have you noticed Toby’s face?”
“Yeah, what’s with him? He wouldn’t even look at me when I walked by.”
“Rumour has it that he’s about to get fired.”