Under Siege (1992)

Erika Eleniak jumps out of a cake, topless. Seagal might be a chef, and it's Die Hard on a boat—but mainly what I remember is: Erika Eleniak jumps out of a cake, topless.

OK, so she doesn't jump out topless, but she does take her top off.
On the latter point the Internet is crystal clear.

You Can Count on Me (2000)

I was one of two human beings in the world who did not like this movie. Mainly I was bored. I think it starts with these two kids finding out that their parents died in a car crash, and then, decades later, Mark Ruffalo comes to hang out with Laura Linney and bonds with her kids—but their relationship is strained, these siblings, and there are laughs and there are tears and ultimately they realize how important they are to each other. Probably he's an alcoholic. Yawn.

An emotionally devastating uncle–nephew bonding scene from the not-at-all-boring family fishing masterpiece You Can Count on Me.

Marathon Man (1976)

Dustin Hoffman may actually be a runner in this movie. Sidney Poitier or somebody is a Nazi who thinks Dustin Hoffman is somebody he isn't, so he tortures him dentally to get an answer to a question Dustin Hoffman doesn't remember. Then Dustin Hoffman basically takes revenge in what I think might be the cavernous basement of a zoo, and Sidney Poitier—wait, does he kill somebody with a sword that comes out of his sleeve? I think everything works out OK in the end.

Did I actually get Poitier and Olivier confused? Yes, yes I did.

Superman IV: The Quest for Peace (1987)

Lex Luthor goes to the Superman museum and steals one of Superman's hairs, which is being used to hold up a boulder. Luthor's plan is to launch a nuclear missile into the sun with Superman's hair in it, and this will result (Lex knows, being a genius) in the spontaneous generation of a new supervillain with all of Superman's DNA but a new costume. For some reason, the new bad guy loses his power immediately if he's in shadow, so Superman puts him in an elevator on the moon. I think some blind girl falls out a window (but I might be remembering some comic book where a weird Superman clone is blown to tiny bits, to white ash, and this rain of super-dandruff gives the blind girl back her sight). There's some kind of "ban the nukes" message to this, and it's very possible that the Superman clone is somehow supposed to be a metaphor for the arms race. Best part of the movie is Superman's hair holding up a boulder. In the end, Luthor is torn apart by boars. I'm just messing with you.

Hold on a second, this looks awesome!

My Own Private Idaho (1991)

Keanu Reeves and River Phoenix are prostitutes. There's some Henry IV business going on, which probably means that Keanu's a wayward rich kid—I think I can see him wearing a suit holding a tumbler of something and ignoring his old friends—and I remember that Julian Schnabel does a Falstaff-lying-about-getting-robbed bit. (I'm sure it's not Julian Schnabel, but I can't stop picturing Julian Schnabel in his goddamned bathrobe.) I think River is narcoleptic and at one point wakes up in a really fancy house. They probably do lots of drugs and everything is homoerotic.

Everything Is Homoerotic by Jonathan Safran Foer

21 Grams (2003)

Oh, man, I think Naomi Watts's husband got run over by Benicio Del Toro in a car, or Benicio Del Toro's friend got run over by Sean Penn in a car, or somebody ran somebody over and then starts sleeping with that person's widow or sister or friend, and somebody else is out for revenge, and in the end nobody's happy. I seem to recall somebody getting shot in a motel room and Naomi Watts screaming. I also remember somebody trying to clean blood off the bumper of a big car. Two-word summary: "Oh, no." (21 grams of what, though, do you think? Somebody's probably a drug addict. Oh, no.)

Everything sucks.

Santa Claus: The Movie (1985)

Santa Claus is recruited to be Santa Claus. Then I think maybe Dudley Moore steals his sleigh. Presumably Santa gets the sleigh back and Dudley Moore learns a lesson, but it might be that Dudley Moore is trampled by reindeer. All copies of this movie in all media have been lost forever, so we'll never know.

Yep. Dudley Moore.