It is a slang term used in essex to mean when you make up a crazy mad, random spontaneous song lyrics with your mates friends.
girl 1: what did you do last night yesterday?
girl 2: I made up a horns on a cow horns on the cow with benji and bob
girl 2: I made up a horns on a cow horns on the cow with benji and bob
by Lennie:) February 6, 2012