the same as a weekday except spent jacking off.
Jackday's are spent usually watching porn (or whatever gets you off), regular tv or movies, gaming, chatting, texting or surfing the net. To be considered a full fledge jackday one must not have any direct human contact for more than 1 hour in a 24 hour period.
to have an EPIC jackday you must have at least 8 sessions within the 24 hour period of your jackday.
if you only have 1 session, that is lame, and not considered to be a jackday!
oh dude, i couldn't stop thinking of fucking samantha i needed a total jackday! if it wasn't for my 'rents coming home it woulda been totally EPIC