The sudden stunned silence that falls on a room after a person says something stupid, unfunny or offensive. Refers to the tumbleweed featured in cowboy movies.

It’s an acronym standing for Can’t Remember A Fucking Thing. It’s usually used to describe embarrassment at being unable to remember someone (CRAFT moment); going onstage as the lead in the latest theatrical performance and your mind goes completely blank (CRAFT situation); the next morning after a night when you got pissed as a fart and woke up in bed cuddling a traffic cone and a string of fairy lights wound round your prick.

The awkward silence that follows a remarkably dumb, over-the-top comment that nobody else in the room seems to understand, find funny or agree with. (Alluding to the "cartoon moments" in which a tumbleweed passes by in the dessert and all you can hear is the wind`s sound)

A tumbleweed moment is when someone says something awkward and nobody says anything for some time.