(as) useless as tits on a bull
(as) useless as tits on a bull
Utterly ineffectual or unnecessary. Primarily heard in Australia. Hey, thanks for the broken wrench—it's as useless as tits on a bull. I know next to nothing about computers, so I'd be useless as tits on a bull trying to figure out what's wrong with your laptop.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.