I'm going to hide my husband's keys so he can't find them in the morning
Why would you do something like that? You do realize he'll be late to work, right?
I want to punish him for leaving his dirty pants on the floor
That is not a good reason to hide his keys. You can be mad at him for leaving clothes on the floor, but what you are doing is too harsh.
It's just a prank! Who cares if he does lose his job?
You should care if he loses his job. That is not a good thing to do to him.