Similar to
dirty stop-out, a dirty stop up is a person who is usually in bed and asleep early but is awake
later much than expected.
A term used jokingly towards another person, normally used by people who are from Yorkshire in the UK.
For example when parents come home from being out for dinner and their children are awake after their
bedtime.
"Oh
you dirty stop up!"
"What time do you call this? You're normally asleep
by now, you dirty stop up!"