There are so many...
Modern memes. When I was into memes, the majority of them were advice animals and rage comics. Now EVERYTHING is a meme.
Shipping real people. Not characters, but people (mostly Youtubers) with other people. It's sort of creepy. Some of there people are married. Sometimes straight people are shipped as gay, sometimes gay people are shipped as straight. I once heard someone who shipped a father with his son.
Pregnant Elsa.
Adults throwing tantrums over kid shows. Yes, adults can watch and enjoy kid shows but seriously when people are ranting and making change.org stuff because "shows today are not as good as when I was a kid" or crap like that, I feel like they need to step back and remember the fact that they are 22+ years old, not 7. Kid shows are made for kids, you (an adult) can legally drive, go to bars, watch R rated films, watch porn, and leave the house without your parent's permission. You can get a bank account and get a Netflix.
"Reblog/Like/Share if you support LGBT rights" or "Reblog if you care if I killed myself". THESE THINGS. They are so pandering and mostly made to get cheap likes. Like do people think if they don't like/share/whatever, people will think you don't support LGBT rights? Like "Oh no, I have to do it or people will think I am a bigot." The second also bugs me because it doesn't actually help the OP. People reblog because they are anti-suicide because "Oh no, I have to do it or people will think I am pro-suicide." It is sort of hard for me to believe that a stranger on the internet really "cares" about you when they know next to nothing about you. Even if the person did die, people would continue to reblog the statement and won't even know but still think they are helping.
Internet reviewers who think a "review" means screaming and waving their arms around and yelling "it sucks balls" over and over again. While it can be funny, it is not a proper way to criticizes a piece, and I refuse to see it as a proper review of the work.