The handle bar that is on either side above a seat in a car, that is used when the driver makes too sharp of a sharp movement with the car, such as a sharp turn, and the passenger or passengers usually say, "Oh Shit!" and grabs onto that bar. Hence "O.S.".

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.