What is Butter My Arse?
An insult to tell some you don't beleive what they are saying.
In other words, the thing they are saying is so unbelievable that you tell them to spread butter on your arse.
Man 1 - Geoffry, i'm gay.
Geoffry - Oh, butter my arse
A state of unfathomability at a comment made in polite audience.
Reg Holdsworth to the Queen: "oi you stink"
Queen: "Butter my arse Reginald"
Term said to a man when their partner wants to engage in anal sex and needs lubrication. Taken from the infamous 'Last Tango in Paris' scene.
"I'm on the blob tonight Archibold, you'll have to butter my arse if you want any."