The fetish called forsitting on the cake is called the sugar icing.
A foot fetish.
An earlobe fetish.
Schediaphilia, is the word for that fetish. It is also know as toonophilia.
No one can say why for sure as with any other fetish, it's so weird it's called a fetish
Fetish for small spaces is called claustrophilia.
There isn't really a special name, probably because it is not very common. It is simply called an elbow fetish.
Remembering that fetish means replacing normal object of sexual desire with the fetish object, I suggest you are seeing the gun as a phallic symbol.
Watersports
That is too normal to be called a fetish. Most men are intensely aroused by the female buttocks and anus.
That's so obscure I don't think there's even a name for it. I think it would just be called a report card fetish.
A piece of cake is simply called (and spelled) "a piece of cake." It may also be called "a serving of cake" or "a slice of cake."
There is a thing called a foot fetish,which is very common especially in male's. I don't have a foot fetish,and I know i'm not missing out on anything. A foot fetish is a sexual attraction to the feet. Usually the feet of a female. Girl's think of foot fetish boy's as "Creep's" or "Weirdo's" and I agree with them. Some has a fetish,and some have disgust. Which I have disgust.