Kevin will go in there, to do what people do in bathrooms. And I will hear "Hi, Ems! Aww...there's my girl..." and then he will begin whistling.
Now, Ems is short for Emily, which is one of our cats. She is the fat one. She is large and black and very sleek despite her weight, and the one one of the horde of cats who is overweight. She's a very nice cat, although a bit shy, but once she happens to be somewhere to be petted, she is a very friendly cat. I am rather fond of her.
She also is driven into mad realms of delight by whistling.
I cannot whistle. I used to be able to, and then I got braces as a child, and one of the casualties of that, along with my overbite, was the ability to whistle. Absolutely can't do it. I think something weird changed in the shape of my mouth or something. (I know, I know, Mae West, "You know how to whistle, don't you?" I can provide signed testimony as to my ability to purse my lips and blow.* I still can't whistle for crap.)
Kevin, on t'other hand, can whistle astoundingly well. Even at my best, I was limited to about one note, but he will sit there on the toilet, and provide a miniature concert that spans Beethoven, Wagner, the Nutcracker Suite, the Imperial March, the theme from the Andy Griffith Show, and other perennial favorites like "Whistle While You Work" and "Pop Goes the Weasel."
After about five seconds of this, the person in the next room--i.e. me--will hear a peculiar accompaniment to this performance, as Emily begins mewing frantically.
It drives her nuts. She stands on her hind legs--and at her girth, this is quite an undertaking--purring thunderously, mewing every few seconds, rubbing herself wildly on Kevin's legs, hands, and at one point during a particularly dramatic rendition of "Ride of the Valkyries," hefted her rather large bulk onto the back of the toilet seat and tried to engulf the back of his head.
She purrs the whole time. She is ecstatic. Whatever this is doing for her, she loves it.
It only works with whistling. Kevin tested this in the interests of science--at least, he claims it was science that caused him to sing an impassioned few stanzas of "Don't Cry For Me Argentina" in the bathroom, and I prefer not to exam the veracity of this claim too closely--and it doesn't do much for her. Let him whistle the opening notes to Beethoven's Fifth, though, and the cat will run from any part in the house--the high-speed, belly swinging waddle of an overweight cat on the move, a run she does not break into for food or fear or any other purpose--and come sit in front of him and sing along with the music.
On the bright side, if anybody ever wonders how Kevin lives with someone as bizarre as I am, I have at least one excellent example of how I'm not the only weirdo in this relationship...
ETA: I am chastised, it was Lauren Bacall, not Mae West. Well, still.
*In several cases, highly enthusiastic testimony.