The law that proclaims that all people are forbidden from sleeping in past 9:00 AM on a Sunday. Despite the fact that people often stay up very late on Saturday, they are not to sleep in on Sunday to catch up on their rest. The reason for this is if one sleeps until 1:00 PM on Sunday they will likely not be able to fall asleep until a minimum of 12-14 hours later - meaning that they will then be very overtired for an early Monday morning of work.
1: Man, that's like your fourth cup of coffee this morning!
2: Yeah, I didn't get nearly enough sleep last night...
1: Really, why?
2: I slept in until 12:30 PM yesterday and then couldn't fall asleep until 2:30... then I had to get up a quarter past 6.
1: Ouch. Well, that's what you get for violating the Sunday Sleep-In Rule.