Lol, the worst thing for me is being relatively sober and sniffing a fat line right before sex, then it kicks in and your a massive hole during sex and coming round 45 mins later think what the fuck just happened! Lucky the girl also had a fat line at the same time so it wasn't too bad! She was my gf so also not that bad, but I have done that to a random girl i'd met in a club, well embarrassing! It was all good in the morning though! 
