I was out drinking one night many years ago right around the time mullet spotting became a meme. Several beers into the evening I spotted a college age kid walking into the bar sporting a classic example of the tennis mullet. Being a service minded individual (not to mention very drunk) I marched over to him and asked him if he was aware he had a mullet and directed him to http://www.mulletsgalore.com/ the next time he was near a computer. The kid looked at me like I was nuts but he wrote the URL down. Mission accomplished I went back to drinking with friends.
A month later at the same bar I was approached by a vaguely familiar dude with a sharp looking haircut. He introduced himself, thanked me profusely for telling him about mullets and bought me a round before joining up with the rest of his friends. Apparently the kid just hadn't heard of mullets yet and I'd done him a real service by bringing him up to speed on the subject.