when one half-peels a banana, and pushes the peeled end into a vagina. Then you continue to push it in, so that the lips peel the rest. then u fuck it and it gets mashhhhed :)
Based on a Craigs' List post. When a guy puts a magnum condom over a banana, does himself in the ass and then deepthroats the banana because he was "feeling slutty".
"Man, I was feeling frisky last night so I decided to magnumbanana myself. I splooged all over my roommates new carpet."
N. Refers to new immigrants from the West Indies to the United States of African decent. Derogatory in nature.
Carl: I just tried talking to that new guy from Jamaica today, I couldn't understand a word he was saying.
Jim: Don't waste your time, I think he just got off the BananaBoat.