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
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.
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.
by bobTheBuilder322 December 4, 2020
person 1: garlic with chicken strips
person 2: BAHAHAHAH
person 3: whats so funny
person 1 and 2: its a inside joke u won't understand
person 2: BAHAHAHAH
person 3: whats so funny
person 1 and 2: its a inside joke u won't understand
by marie8829 March 20, 2023
a joke made by 2 or more people that only that group understands! even if you explain it to other people they might not find it as amusing as you would.
Person 1: "ahaha horsepower"
Person 2: "what??"
*inside joke is explained*
Person 2: I don't get it
Person 1: it's an inside joke
Person 2: "what??"
*inside joke is explained*
Person 2: I don't get it
Person 1: it's an inside joke
by imBDS December 20, 2019
by AnyaForger May 8, 2022
The thing that Urban Dictionary hates and will not let you publish a definition if it includes an inside joke
by nabrU yranoitciD January 13, 2020
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 27, 2019