A term used to denote one's stupidity; mentally handicapped by the amount of pebbles and sediment in their cranium.
Guy 1: I've really gotten into THING I DISAGREE WITH.
Guy 2: LOOOOOOOOLLLL shut the fuck up, you stonebrain-ass bitch. How much sediment you got up there, huh? I can see pebbles coming out of your ears, bro.
This occurs when your partner is wearing a Canadian tuxedo have the them put a large handful of sunflower seeds in thier mouth; once the mouth is good and salivated have them begin blowing you. This process continues until the recipeient screams " I give up!!" at this point blow your load on ur partners face giving them a sunny delight.
I was at the store saw some seeds and thought tonight would be a great night for a Slobering Sunny Perinto.