1) To roll in your car with drugs, guns, or other shit you don't want the cops to find. Usually drugs.
2) To not have taken a shower in awhile or wiped one's ass properly.
"They see me rollin', they hatin', patrollin'
Tryin' to catch me ridin' dirty."
(Chamillionaire - "Ridin' Dirty")
Jim: "Hey, get your ass over here. There's grippa
bitches. What's taking so long?"
James: "Give me 20 minutes. Gotta take a shower."
Jim: "Dude, you don't need a shower. The party's not gonna wait."
James: "No, you don't understand...it was chili con carne night and we're out of T.P. The neighbors came over to complain because they thought someone was playing the trumpet terribly while firing a machine gun."
Jim: "OOOOH yeah, good call. You really don't want to ride dirty like that."