Pavlov would be proud.
When I was in college, I took a sociology course with my girlfriend where Pavlov's experiments were taught and discussed. During class, I looked right at her - because I'm depraved - and said, "I'm bringing a bell to the bedroom, and every time you bingo I'm going to ring that bell. THEN, after you've learned to associate the bell with the bingo, I'm going to start carrying it into social situations. Parties, Thanksgiving dinner at your Mom's house, etc. OR ... you can give me a blowjob in the car before we go to the next class".
Never bought the bell. Good girl.