Obligatory bathtub masturbation scene
Well, so much for my attempt to avoid references that no one will understand.

(If you want the explanation: A long time ago, I was reading a review of some post-Basic Instinct Sharon Stone movie in the Chronicle -- I don't remember which one it was, possibly Sliver -- where the reviewer said something like, "After the obligatory bathtub masturbation scene, such-and-such happens." I found that to be a rather odd turn of phrase. The next day, I found out that Jon Carroll agreed with me, since he also wrote about its oddness in his column. Aaaanyway, I figured that since I'm covering all the obligatory bases, that seemed like the logical next step.)

(Disclaimer: No actual bathtub masturbation occurred during the writing of this post. Well, I suppose some did, somewhere, but not in my bathtub.)