closed for a what

There are two possibilities I can come up with for this sign:

1. The person whose job it is to put the letters on the sign was brutally tired to the point where only their morning coffee was keeping them awake, and they just put "poop" without thinking.

2. A customer from the day before blew up the bathroom — figuratively, of course.

or it was a group of teenagers who made the letters say that

finally they're remaking their poop. about time!