The best friends are the ones who give you a hard time when you talk rubbish. Who don't roll their eyes (too badly) when the 3 a.m. text comes through saying 'I need to talk to you now'. Who catch your eye at a social gathering when things are a bit tricky biscuit and make you bite down on the inside of your lip so that you don't snort with inappropriate laughter.
They are the ones who catch you when you fall. And fall hard.