Search up "meme" in community search, subscribe to all the ones that interest you. Unlike 9gag, which just feeds you a stream of posts, you need to be proactive in knowing what you want and finding it. To a lesser extent, Reddit suffers from the same problem. (Though my understanding is that Reddit is becoming increasingly curated, making Reddit increasingly like 9gag in that respect). Regardless, with this type of social media, the 2 biggest ways of finding communities are to actively look for it yourself or to find out from a someone else.

It can also be a good idea to look at c/trendingcommunities@feddit.nl to keep updated on new communities