who knows what
see under what have you.
Words nearby who knows what
whizz-bang, whizzer, whizzo, whizzy, who, who knows what, who'd, who'll, who're, who's, who's afraid of virginia woolf?
The American Heritage® Idioms Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
Examples from the Web for who knows what
Like mushrooms, in a single sight we spring up—a pen in our hands, very little in our brains, and who-knows-what in our hearts!
The Complete Essays of John Galsworthy|John GalsworthyThe little model gave him a look with who-knows-what of reproach in it, and, faithful to her training, went submissively away.
Fraternity|John Galsworthy