I.B. 

Kids with giant ass backpacks that usually go out 3 times their body's width.Usually resulting in back problems in the future.

That bag is frikin' huge. It's really I.B.

I.B. by Gojitte March 26, 2007

I.B. 

A substitution of the first two letters of "irritable bowel" as the initials of someone who always has to take a shit at the worst time

I.B. Clarkson (Irritable Bowel Clarkson) could not hold it until the next exit, so he had to take a shit in the woods.

I.B. by scroty G October 6, 2009

I.B. 

INSTANT BONER- refers to a female that can make a mans man stand to attention..

As soon as Alika walked in the room i knew she was an I.B.

I.B. by j*rocktrixxxkilla May 21, 2008

I.B. 

Abbreviation for in bed. Usually safe to use when within earshot of parents, teachers, or anyone else who may disapprove if they heard the actual joke.

Student 1: "All this work is killing me!"
Student 2: (notices teacher nearby) "I.B."

I.B. by whohastoknow January 24, 2011

I.B.T.C.

Ittie Bittie Tittie Commitee

Not Only Is She A Memeber Of The I.B.T.C.,
But She Is Also The Presedent.

I.B.T.C. by Arrow April 24, 2004

I.B.I.S.H. 

"I Believe In Sherlock Holmes."
A saying that many Brits have been saying after BBC's Sherlock's (2nd) Season Finale had aired. They started saying these things because on the episode, Sherlock died in disgrace, everybody believing that he had made Moriary & other cases up in order to gain more public popularity.

A sign to others that you are a Sherlockian.

(In other cases, "Moriarty Is Real" suffices as well.)

"Ugh," says the non-believing ninnymuggins. "Sherlock is a fraud, he killed himself just because things didn't go as he schemed."

All of a sudden, a Sherlockian fangirl appears and shows the non-believing ninnymuggins the badge on her shirt. 'I.B.I.S.H.' was written on it in beautiful magic markers.

"MORIARTY IS REEEEAL!!!" Says the fangirl, and she throws a BAFTA at the non-believing ninnymuggins in anger. "Fuck you, Martin Freeman won a BAFTA!" She screams, then walks away proudly.

I.B.I.S.H. by danceisaspork February 5, 2012

I.B.S 

Itchy Ball Syndrome.

1. One suffering from lack of sex, usually of the male gender.

Man 1:My god, I've got a bad case of I.B.S
Man 2: Wow, how long has it been, man?
Man 1: About a week.

I.B.S by Zhyre December 26, 2007