where usually during dances/parties/clubs a girl presses her butt on a guys crotch to achieve a profuse erection
generally hip-hop/pop/tech/etc. music plays in the background, but if shes good she will move with the beat and depending on the man he will like it slow and sensual or rough and to the point of breaking your dick
black girls are usually best at this since this it is their genre of music generally and they hit almost every beat, followed by latinas, then asian and white tied after (generally speaking) although asians and white girls tend to be prettier to look at
uncreative minds will only hold the hips but it can expand to hand holding, touching the girl, grinding face to face with her vagina getting involved, getting on the floor chris brown-ing her (take you down), etc.
damn i was grinding for the 1st time with ashley yesterday it was awesome!