The Intersect is a government super-computer. It holds all of the government secrets. The Intersect was downloaded into Chuck Bartowski's brain when CIA agent Bryce Larkin steals it, then sends it to him via email. With the Intersect in his head, Chuck can "flash" on all of the information when he sees or hears something that is recorded in the program. With the Intersect, Chuck becomes a major help for the CIA and NSA and receives a CIA handler, Sarah Walker, and a NSA handler, John Casey.
In the last episode of season two, Chuck downloads the Intersect 2.0 and is then able to flash on martial arts, foreign languages, how to properly use weapons, etc., etc.. Once Chuck has the Intersect 2.0, he later becomes an actual CIA agent.

area between nutsack and ass hole

An intersection is when two men and a woman are having sexual intercourse, and instead of spreading the woman's ass cheeks, one of the guys spread the other guy's ass cheeks.

When you're eating a girl out and you intersect your way from the pussy to the asshole without removing your tongue and then start eating the booty like groceries.

Protection racket where disadvantaged groups, whether real or perceived, sell protection from false hate accusations for concessions from others.

when you're in a sick car, coming up to an intersection, you're praying for a red light so that when you stop everybody is looking at you in your car, then it's your time to play the hottest song: intersection music.

getting all the attention you want at the intersection w/ a hot song

The scurry for new sources that arises when demand for oppression outstrips supply