I got it!

"Whats a mouse when it spins" is a anagram.
But what does it mean?
Follow the deciphering...

What's a mouse
when it spins

rearrangingly becomes...

A tsuwm's a hoe
when it spins

rearrangingly becomes...

"a tsuwm's a hoe"
ain't hip news

This is strange because a tsuwm is not a hoe.
Everyone knows that a tsuwm's a rake.