The act of spelling out the alphabet with your tongue while performing fellatio.
"Bro, I went down on this chick Barney Style and she came like a waterfall!"
"I tried to give it to her barney style, but my tongue got too tired halfway through."
This phrase is used when you are about to explain something to someone in very basic terms because anything too complex will confuse them, or already has confused them. Frequently used in the military. Does not usually have anything to do with sex.
"Alright, since my first explanation didn't seem to sink in for your morons, I'll break it down barney style for you."