Short for "I see pee" most likely said in a messy restroom by someone who would pay attention to that.
Could also say
1. I notice urine
2. I observe piss
3. I view piddle
4. I discover weewee

icp is short for Insane Clown Posse

They are a rap duo from Detroit ( whos stage names are Violent-J and Shaggy-2-Dope ), who have made themselves infamous for a number of reasons

1) thier striking appearance
2) thier fanbase
3) thier wigger-ness

lets look at these reasons in detail.

1) The icp wear face paint, a base coating of pure white all over thier faces, and then their respective patterns painted on in black, sometimes with an extra colour to match thier outfits. For a while, both of them had long dread locks aswell. Nowadays, Violent-J has bleached spiked hair, while shaggy has braids.

2) Thier fanbase (refered to as "Juggalos" for guys, and "Juggalettes" for chicks) are the biggest reason this band is as hated as they are. Juggalos and Juggalettes are all dipsh!ts... thats what it boils down to. You can be damn sure that anyone who refers to themself by this term, is a total loser. Juggalos will wear face paint, all day. Its one thing to wear the paint for an ICP event, but Juggalos will walk around all day with the stuff on.

They are all incredibly defensive when it comes to icp, which is admirable, if they didnt have the debating skills of a head of lettuce. For an example of a Juggalo's argumentative skills, see below

There is nothing wrong with ICP, but the average member of thier fanbase is a moron, which in turn will reflect on the band themselves

3) Shaggy and J both talk like a pair of wiggers, and really, they are...

BUT !!!!!...

Insanely Comfortable Pants

Often used nickname for Insane clown Posse fans, but really the word for Internet Child Porn.

A rap/hip-hop duo consisting of two Caucasian males from Detroit. Their fans, known as Juggalos, are very defensive but can't seem to type very well. Their detractors sometimes have a problem spelling as well, but the general opinion of this band is that you either hate them with a passion or love them with a passion.

Short for Insane Clown Posse. Basically a couple of white boys who make terrible music and look like they have jizz on their faces all the time. They also have a fanbase of dipshits like them.

A rap duo from detroit consisting of two of the smartest caucasians I have ever seen in my entire life. What they do is make a few off-tempo beats that could easily be bettered on a child's toy keyboard, and scream and talk about random shit they think about when they get high on peyote about clowns, then they'll put it on a cd, slap on a couple ugly pictures of themselves in retarded clown garb, and make millions from retarded white emo kids who don't know any better. They get rich off of being worthless.