Similar to the basket ball game accept played in a night club with chicks...A group of guys (that have swagger) take turns approaching women and trying to pull of gratuitous 'shot's without bricking / getting rejected, ie. kissing, groping, hugging, dancing, etc.
Once a guy pulls off a 'shot' with a chick, the following guys have to attempt and make the same 'shot' with the same / different chick or get a letter.
After their first round at the bar, the group of guys decided to play H.O.R.S.E. Justice was first and approached a girl he didn't know in the club and starting kissing her with tongue without getting rejected...Jeremy was up next and had to pull of the same 'shot' or get a 'H'.