Tip drill

[Jessica]

A tip drill is another name for runnin a train on a girl.
Comes from baseketball where players line up at the free throw line and tip it off the backboard consecutively, one after another.
Think of it in the sense of a group of men runnin a train on a woman. First man in line hits, next man follows until everyone has had a turn...
If the nelly song is the first time u have heard this term try listening to the lyrics more carefully. Just cause they say it must be your ass cause its not your face doesnt mean a tip drill is a chick with a big botty and an ugly face.

[Sonia]

When a girl bends over and her man puts his penis in her ass crack without any penetration. This is usually done as foreplay before [doggystyle] sex or as an act when the man and the woman do not want to engage in full intercourse. It is the ass equivalant of a [titty fuck]. The womans ass cheeks are used to excite the penis, sometimes to ejaculation. Her ass is polishing your tip.
ALSO, a girl who has a nice ass. This is because a girl needs a nice ass in order for this act to be pleasureable.
Many people confuse this word for the equivelent of running the train. This is because this act is used by many men on one woman on after the other. This is common because a tip drill does not involve penetration, making it easier to be repeated on one girl in a short amount of time.
The act is mock performed in Nellys Tip Drill video. Also, the video focuses on the ass crack and at the end, Nelly swipes a credit card on a girls ass, simulating the act.