My goodness, so how did you handle it? If one of my boys ever did that I'd probably scream my head off, hence scare them, and I'd kick the rat out the door. They wouldn't be allowed outside until my bf tosses it somewhere else.
Sadly my bf is off on a "boys trip" half way across the country so I grabbed a grocery bag, paper towels and disposed of it. My PITA neighbors had left their garbage can out so I put the offending creature in there.