"That meme is dead, Mum."

It was the moment I realised I really was profoundly uncool, expertly owned by my 16 year old son. I was using a meme that was tired, apparently. Overused. About to become the territory of that Aunt who posts Minions memes on Facebook. It was dead.

But how long do memes live for anyway, and which ones endure the test of time?