To assume privileges that have not been bestowed upon you.
To get above your station
OI ! I was watching that !
Who's house do you think you're in in man ? Seriously, that was bare berties. Get the kettle on.
Oh right, yeah help yourself to angel cake, dont mind me. Is this a sponsored bertathon ?
Berties is the code for bullshit. Derived from Berties Bullshit.
Give him the royal berties, he'll never know.