Mop the Floor with the Mops
From A KoL Wiki

You enter this level of the basement and find that it's filled with magically animated filthy mops. There appear to be about n of them.
Some filthy moppet must've borrowed his master's hat and set them to work making the floor dirtier. Looks like you'll have to magically de-animate them if you want to get through.
You recall, using your prodigious memory, a spell designed to de-animate household cleaning products. You cast it, and the mops collapse to the ground, as dead as a group of 23 dead doornails.
You head down the stairs.
Occurs in Fernswarthy's Basement.