Let that sink in meme
Warning: this post contains hyperbole. Don't read it if you are too stupid to know what that means.
This is a meme, and also a pun. The humor in this meme is twofold. First I'll talk about the pun: "Let that sink in" is a colloquial phrase that means "Take a moment to think about that so that you will be able to understand it". Another interpretation of the phrase could mean "I want you to allow that sink to be able to come inside". This meme uses both of those interpretations of the phrase, the first being written before the second. It is a humorous juxtaposition of the two meanings.
The second thing that is funny about this is the absolutely awful quality of the image editing used to create this meme. It is really truly horrific, and that it about the funniest thing ever.