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
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
by Uncreative Blob February 7, 2018

by TheAssEater2000 May 17, 2016

"Oh, look Jhon, they wrote John on the bowling alley screen, now I will occasionally call you John pronounced JO-HNNNN, forever on, this will be an inside joke!"
by reallyunfunnyguy December 7, 2023

by Dream_69 October 16, 2021

What happened to your friends face.. He was pulled insde the gate
You shouldnt go that way you can get pulled inside the gate
You shouldnt go that way you can get pulled inside the gate
by Cpt Bomba March 8, 2022

Definition of an activity that can only be played indoors such as Fortnite or League of legends, which are clearly a total waste of ones life
“Your insideness is ruining your life - get off the Fortnite, out of the house and do something useful”
by rusty3105 December 26, 2019

A specific type of joke where you name a part from a very specific model/year of car as part of a sex joke.
'I can't bust a nut without a poster of 2001 Toyata Corolla wrapped around my head'
'Well, I can't orgasm without a windshield wipe of a 1998 Bentley Arnage up my ass.'
'Those are Car Insid-'er Jokes'
'Well, I can't orgasm without a windshield wipe of a 1998 Bentley Arnage up my ass.'
'Those are Car Insid-'er Jokes'
by The Final Girl Support Group July 19, 2021
