Subscribe to PewDiePie

Listen up, buttercup. The joke here is that the user is telling everyone to subscribe to PewDiePie. PewDiePie used to be the most subscribed channel on Youtube. He had beef with another channel called T-Series for the top spot. When someone says subscribe to PewDiePie, it's usually just a joke or meme. Now, go back to watching your cartoons, you cotton-headed ninny muggins.