72 hour vacation

A reference to the length of time a person can be involuntarily admitted to a psychiatric hospital for observation.

The suggestion is the person you are dealing with is acting in such a bizarre and/or aberrant behaviour that they should be put away for observation.

1st Dude: Let's trash a few houses this weekend and start some fires.

2ndDude: Dude perhaps you need to take a 72 hour vacation.