1) Things which are not actually fails. Okay: if you are swinging from a rope and intending to fall in the water, and you actually do this without any complications, then it's not a fail, regardless of how you land. Likewise, if you're jumping some vehicle off a ramp and landing in foam blocks or an airbag, and you actually land in the designated landing area, it's not a fail. Doing what you intended to do is not a fail, by definition.
2) Dogs humping things, including other dogs. There isn't anything funny about this. It doesn't matter if the dog is humping someone's leg, a non-dog animal, another dog, or a wheelbarrow; this isn't funny.
3) Nut shots. Or, in fact, anything involving injury or pain. I don't think it's funny when people get injured or hurt or break teeth, particularly when it's because they're attempting some silly stunt.
4) Practical jokes. Removing the support slats from someone's bed, or just putting on a mask and scaring them. It's not funny. (This includes the practical joke with the water bottle. Who still falls for that?)
5) Movie clips. Or cartoon clips. I watch these things with the sound off. 99 times out of 100 the movie clip adds nothing to the video. And they're annoying.
6) Babies barfing. There isn't anything funny about that, regardless of where, when, or what they puke. You only think it's cute when it's your kid, and then only the first couple of times.
7) Toddler trying to drink and failing. Not funny. In fact, most kid fails involve toddlers--who do not have the best coordination--trying to do something, and they are only failing because they're practically babies. There isn't anything funny about it. The same thing goes for video clips where a kid has painted the TV, or spread baby lotion all over the floor, or-or-or. It's not amusing; it's not even cute--it's just a huge mess.
8) People under the influence of anasthetics. These people are literally mentally incompetent due to the drugs that are still in their systems. They can't help saying what they say; the drugs have turned off their internal censor and they say whatever comes to mind. Their intoxicated babble is not funny.
9) Breaking TVs. The kid throwing the game controller, the guy throwing the beer bottle, whatever it is--I don't think it's funny when someone destroys a TV even if they're having a temper tantrum about something idiotic.
And just to make it an even 10--
10) Music. This is why I turn the sound off: the music is idiotic. Unless it's "Yakety Sax" used judiciously, it adds nothing and just annoys me.
I do get a laugh out of these things, but not at anything from those categories.