The act of an adult having any kind of sexual relations with a minor. For example, if your 20 or so (or 30, whatever floats) and some smokin' 16 year old is all about hooking up, you may decide to throw causion to the wind and hit it anyways. That, friends, is Dipping Down.
Dude, this chick is drolling over my cock, but she's like 15! Even though it's technically illegal since i'm 19, I'm dipping down anyways.