Old jokes

You know those jokes in high school that were just between you and a friend and that were OH so funny?

I must be getting old, because I remember the jokes, I remember that they were funny, but I don't remember how we got to the joke in the first place, or what it meant.

For instance:
The Seven Dwarves of Jiffy Lube: No idea, I just remember it was funny at the time.
Grover the Clover - It rhymes, hence the humour: this was funny just because Lee said "hence."
The Banana Snake that lives in my brain: Again, no idea.

At lot of these made their appearance in my "Senior Will" which was basically a way for the seniors to inform each other they each had private jokes, and could exclude somebody, somewhere. Ahhh the thrills of high school. Remind me again why it was fun?