A joke that only a certain group of people will understand based on an experience the group had.
Person 1: Remember when…
Person 2: Shiiit I remember haha.
Person 3: What the fuck are you guys talking about?
Person 1: You weren’t there to see it, it’s an inside joke.
Person 3: Fuck well don’t I look dumb.
And inside joke is something that Urban Dictionary doesn't allow in their definitions.
Urban dictionary: "Don't name your friends. We'll reject inside jokes and definitions naming non-celebrities."
Me: "Ok."
A joke that only a select group of people will get unless it is explained to someone else.
Guy 1: “Hey Susie! Fish without meat!” *laughs*
Guy 2: “What?”
Guy 1: “It’s an inside joke between us”
A joke that is a very bad joke to everyone except you and your ex, so you have no one to enjoy it with :(
The inside joke I had with Cheryl was quite funny. I miss Cheryl. :(
When you have so many inside jokes with someone you can't keep track
Liberty and I have so many inside jokes including "omg im so popular"i can't keep track of all of them
An inside joke is something used to exclude others out of conversations and to strengthen one's own friendship, which is why humanity is extremely selfish. However, others can be included, but they feel awkward.
"I'm going to eat curry with some more curry and pizza when I fly on this airlines called Fly Curry Curry Pizza 2.0. The airlines is a group of people meant to manipulate several people for one's gain and basically serves various kinds of food, including curry and pizza. It's imaginary, but you know where this inside joke comes from since you are my friend." -friend #1
"Hahahahahahahaha! The airline also gives free ipads in-flight and donates to various countries and is very cheap!" -friend #2
"I'm gonna walk the dog now. Then I'm going to take over the world because of modern day politics." -random person