When someone puts a dip, or chewing tobacco, in therebutthole, then a friend takes the dip out with their tounge and returns it into the other persons lip to be enjoyed.
Greg: Tyler, my but still stings from dip diving lastnight.
The act of placing a dip of chewing tobacco into ones butthole, then proceeding to take it out with your tongue and returning it into your partners lip to be enjoyed.
Greg: I shouldn't have eaten taco bell before we went dip diving.