A handjob performed while both parties are standing up.
The first known occurrence took place in Fulham, London during 2015 where the standy j was executed against the living room door to stop fellow housemates in the room. The standy j was finalised with the recipient catching his own nectar, thus keeping the carpet stain free
We were having a tickle fight and before I knew it, she stood me up and gave me a standy J.