How do i get my brother to stop being a pervert?

my brother is the biggest pervert ever! he's only 8 years old and talks about 24/7. he knows things not even a 20 year old should know. like a dirty sanchez or 69 he knows what that is. and before you blame me he learned from the older kids at school. how could i get him to at least never talk about any of that stuff until he's 18. pleez help before i lose it and beat the crap out of him