Urban Dictionary: I.B.

1.	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. buy i.b. mugs & shirts book worm overly smart person geek spaz international bachalaureate by Gojitte Mar 21, 2007 add a video
2.	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. buy i.b. mugs & shirts poop irritable bowel syndrome crap fecal postion rock the house by scroty G Oct 6, 2009 add a video
3.	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. buy i.b. mugs & shirts boner erection woody hottie boneable by j*rocktrixxxkilla May 21, 2008 add a video

4.	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." buy i.b. mugs & shirts in bed abbreviation innuendo dirty joke euphemism by whohastoknow Jan 23, 2011 add a video