Canadian rapper Maestro can be credited with coining the term although now popular amongst various rappers such as the Ying Yang twins.
After pulling a prank in a public washroom which involved leaving an unsightly item in a urnial, Maestro passed a local patron, patted him on the back and said "Its all yours, Billy Ocean"
-Billy Ocean is the Canadian equivilant of Nah Mean
or Nam Sayin
-Can also be used to sum up a situation, moment, mood or feeling
-In place of nah mean
:"Yo, the washroom is all you, Billy Ocean."
-As a description: "That cat had me straight vexed like Billy Ocean"
-As A Question: "How was the party? Billy Ocean?"
-As An Answer: "It was so Billy Ocean"