Rob Kardashian -- Reportedly Cited for Tint

Rob Kardashian learned an interesting lesson yesterday ... when you go black, sometimes you have to come back ... because he was reportedly nailed for driving with tinted windows.

The Bev Hills cop was unsympathetic to Rob's quest for vehicular anonymity and served up a citation.

Big sis Kim was luckier Monday. A cop gave her a warning to lighten it up ... then sent her on her merry way.

Kim always seems to get off.