When you look at someone and you think wow that guy's dirty.

This could be attributed to outer appearance or actions such as having a dirty mustache, driving an IROC or wearing an acid washed jean jacket.

Also can be used when referring to a meal, such as a KFC double down, or a super big mac followed by a 20 piece chicken mcnugget.

-- The name given to someone you first really fooled around with.

-- You know it happened, but are damn embarrassed.

-- This person is usually a bit nasty.

-- "The one...? wtf"

-- A name given if you are Chrissy French.