[Help] Clean "long jokes" for family campfire

I have no idea what these types of jokes are called - so I'm likely just looking for the right subreddit (but I did check /r/long_jokes, /r/longjokes, and /r/longerjokes - all turned up to be dead ends. /r/cleanjokes has promise, and I'll spend some time there).

Hopefully the fine members of this sub can:

1. help me name this *type* of joke to make my search easier, or
2. point me to the perfect subreddit I didn't find yet, or
3. tell me that a good campfire joke-teller can expand any joke into the type I'm looking for.

Now, what I'm after are jokes that are family friendly, can be easily expanded based on the creativity of the teller, and have a simply understood pun or punchline at the end to generate a good groan/giggle for 7-70.

I found a few examples of short versions of jokes I have told in the past that I've expanded quite a bit with creative "backstory":

* [A snail walks into a car dealer](https://www.reddit.com/r/Jokes/comments/1uia6a/a_snail_walks_into_a_car_dealership/)
* [A story about a rope](https://www.reddit.com/r/Jokes/comments/1fz0k9/a_story_about_a_rope/)

Thanks for the help!


Edit : https://www.reddit.com/r/ShaggyDogStories/