| Idiom | Meaning | Example | 
| what was I thinking of | 
why did I do that? I wish I had not done that
 | 
I got my head shaved! What was I thinking of!
 | 
| what you don't know won't hurt you | 
if you do not know about a problem, you do not worry
 | 
Don't tell Dad I'm gay. What he doesn't know won't hurt him.
 | 
| whatever floats your boat | 
(See float your boat)
 | 
 | 
| what's cooking | 
what is happening, what's going down
 | 
What's cooking with the kids? They're too quiet.
 | 
| what's eating you | 
what is bothering you? are you upset?
 | 
What's eating you, Darryl? You look kind of mad.
 | 
| what's going down | 
what is happening, what is going to happen, down the pike
 | 
The students want to know what's going down - where the teacher went.
 | 
| what's going on | 
what is happening, down the pike, what's going down 
 | 
I want to know what's going on. Who wrote this note?
 | 
| what's good for the goose is good for the gander | 
rules that apply to the wife also apply to the husband, tit for tat
 | 
If you need a holiday, so do I! What's good for the goose is good for the gander.
 | 
| what's-his-face | 
what is his name, I cannot remember his name
 | 
Nobody can park here, not even old what's-his-face - the judge.
 | 
| what's in it for me | 
what will I receive? how will I benefit?
 | 
Before I give you the information, what's in it for me. Do I get paid?
 |