The use of the word "cuck". By this point, even seeing it used correctly.
I can't help but to feel bad for the actual cuckolds out there. It seems like finding research is going to be harder now than ever before.
If the meme is the punchline, it's probably not very funny. Damn daniel was never really that funny since you couldn't do anything creative with it. It was purely referential. Same with deez nuts or anything like that.
Harambe jokes can be pretty good, if only for the absurdity of it all. There's no good reason why anyone should care about a gorilla, so the underlying joke is that everyone is pretending that it matters. There's some good jokes to be made about the whole situation.