*you turn the key and pull it out of the ignition, silencing the purr of the engine. In the passenger seat, the point leans over and thanks you for all your effort before opening the door and leaving. The point approaches its house and thinks about how happy it is you drove it home*
Just realized I totally read this wrong and mixed up the roles a ridiculous amount. By he I meant she and by wife I meant husband, thanks for understanding.
"Interestingly, my wife has a birthmark in the same place. I wonder if I passed down a genetic predisposition to finding mates with that birthmark attractive… Well, anyway, you should probably leave. Wouldn't want this to be weird."
Did you think the shower turned itself on or something and didn't feel the need to at least put something on to go check it out? Seems like common sense to me.
I expect that since she has a father in law that she also has a husband.
The natural thought process then is that the husband is the one who turned on the shower and that it would be fun to join him.
Be prepared for some awkward eye contact between you and your father-in-law. The best thing to do is to talk to him and explain what happened and also tell your husband so that in the future, he will hopefully inform you of anyone staying over. I'm sure it was as awkward for your father-in-law, as it was for you. It still sucks though, OP, hopefully something like this, won't happen in the future
Maybe I'm reading this incorrectly, but it sounds like YDI to me.