The result of shooting a load into a chicks ass while she's shitting on your dick. Similar to a dirty sanchez on your cock, or to a shit dick, but with more liquid.
I had to wipe the analgravy off my dick before I went back to the girlfriend.
"anal wash" is where you get a bottle of water either with a straw or a just the normal end of the bottle and insert into the anal hole, slowly squeze to insert water into anal hole. once finished, push the water out of your ass either for the pleasure or to swill the inside of your ass clean. this is usually a really pleasurable experience. this is a good thing to do to both partners.