[KevinB]

He’s about as useless as teats on a bull.

I used to work in an office which had a secretary with the last name Bull. Let's just say that nature had been very kind to her when it came to certain aspects of her physique. Ever since "useless as teats on a bull" is an expression that I am unable to use.

[Gaffer]

I can understand that, certainly! But in my lexicon of the colloquial vernacular, it is entirely appropriate. :o)