When you stay up on TSR late at night because your house hasn't turned the central heating on at night - and you just don't want to strip and climb into your freezing cold bed..
edit: Sadly, 4 years later, this is still relevant.
- you live off soup for several weeks because you can't be bothered cooking 'real' food. - you start to clean and tidy every inch of your room and willingly do every chore you could possibly think of... just so you don't have to study/work on assignments/etc. - you have a sick bucket next to your bed, just in case.
When you go to sleep at 5:30am and are up at 7, then sleep during the day You wake up with strange bruises, strange phone numbers in ur contacts and wake up in a random house You are used to watching a broken tv "Cleanliness" is simply out of sight, out of mind Music is on constantly You argue with parents about the taste of alcohols (whoops)