A fuller version of his spiel is below if you want a better context.
I need to brace myself like that guy recommends because tomorrow evening my daughter is having her birthday party at our house. It's a theme party. All twelve girls coming over for the party and sleepover were given Clue-like names, such as Miss Scarlet and Miss Violet, and they will be put in pairs to solve this mystery: "Who killed my little brother?" The rooms of the house have different names and will have clues in them.
The dead brother in question and I are leaving after the party gets started to take in the revived football rivalry between Charleston and Mattoon, the "Coles County Clash."
Mrs. Nasty also found out today that a joke she told our daughter is being taken seriously for humorous effect. At a previous birthday party, apparently there was some drama between a few girls. Mrs. Nasty told our daughter, jokingly, that if anything like that happened at her party, that she'd "hose down" the offending parties. Tonight one of the moms of my daughter's friends told her that our daughter has been telling her friends that they need to take an extra set of clothes in case they have to be hosed down. I plan to have some fun with that image as my boy and I leave for the game tomorrow night. As we part ways, I might say something like, "I hope you are all good. I wouldn't want any of you to get hosed down."