A sentence enhancer, or a sentence in it's own. Can be used as a greeting, departure, or to smooth rough ties between people and shut others up. It's a movement. Usually followed by a fist in the air.
"RollTide?" "RollTide!" (Black Power Fist)
The act of sticking your penis in someone's ass, as they the roll around violently.
Jeffrey likes to rolltide his mom on Wednesday.