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.
example:
"I said it ain't no fun less we all get some I need a tipdrill, we need a tipdrill "
People who you grew up or with or know that you called aunt or uncle or cousin or some other family relation name when they're are not a blood or lawfully related person.
Well I mean, she's not my "real" cousin, we're not related in any way by blood or marriage. You know, she's fauxmily, so it's not weird that we made out.