unbutterable 

A person who is not susceptible to another persons attempts to be buttered up

Trying to butter me up innit……unfortunately I’m unbutterable

unbutterable by Specky1984 February 21, 2014

Unbetterable 

Not able to be improved

That article is unbetterable

Unbetterable by Tiggerr August 10, 2012

unuberable 

Adjective. A person that has become so inebriated that they shall with some certainty vomit in a ride-share, rendering them disqualified for this mode of transport.

"Jacko's UNUBERABLE mate. He's gonna hurl for sure"

unuberable by miiikey May 8, 2021