A joke pertaining to a friend group or online community, through which it is exchanged exclusively. Similar to memes, but more specific to a smaller, more clearly-defined group of people.
friend 1: "Guess it's time for you to go get your own boat, then!"
friend 2: "Ha! You smartass, you!"
stranger: "Uh... was that a joke or something...?"
friend 2: "Oh, it's just a silly little inside joke. Don't sweat it."
When a small group of people make up a joke (a phrase) while no one else is there (Sometimes because of an event that occurs, and then someone says something and it becomes an inside joke) and don't tell anyone about it, so every time anyone (whether from the group or not) says the phrase, they all start laughing like idiots for an unknown reason. It completely baffles people outside this group why it would be remotely funny. Most of the time it confuses them, or annoys the crap out of them.
Jeff started cracking up for no reason when I said "jelly"
Like wtf? Is that an inside joke?
Person 1: So I spread mayonnaise on my turkey the other day...
Person 2: Ahaahaahahahah!!! MAYONNAISE!!!!
Person 1: Wha-
Person 3: DID HE JUST SAY MAYONNAISE??!! AHAAHHAHAHAHAH
Person 1: Um??
Person 1: I checked out books from the library for my little brother, he seems to like The Very Hungry Caterpillar
Person 2: HAAHHJHSHJAHJDJHGGJDG HAHAAHHAHAHHA S SHAHAHAHAHAHHA
Person 3: *wheeze*
Person 1: .....
Person 1 walks away
A joke that a certain group of people get until explained
(Kyle) Hah, like Ankle Phone!
(Jocelyn) Yeah!
(James) What?
(Kyle) It's an inside joke, we saw it on an ad where a guy had a phone on his ankle.
(James) Oh. Thats not funny.
(Jo&K) Fuck you
A joke that a group of a minimum of 2 people understand. And only them, although Urban Dictionary doesn't like them.
Me: “That spa-“
UB: NO INSIDE JOKES *deleted*
Something that only a particular friend group or select few would understand.
"...I don't get it" "It's an inside joke. You just had to be there"
Everyone seems to be in on it except you
Person 1: Ugh what did you get on the math test?
Person 2: Utah, duh.
Person 1: HAHAHA THATS SO FUNNY OMIGOD
Person 3 (you): Um how?
Person 2: *sighs dramatically* It's an inside joke.
An inside joke is a joke that is only funny to a select group of people.
This is an inside joke. Urban dictionary should not approve it