Redditism 1: "It's the internet. You are allowed to swear." 
I hate when some very grown-ass adult says that because someone didn't cuss enough for their taste. I swear all the time in my posts here but I still find that shit really, really tryhard and it seems more immature than not saying the naughty word to me.
Redditism 2: Ending a rebuke with a question mark when it's not a question to make it sound extra snippy.
I've heard this being compared to a "vocal fry" and maybe it is, and coming from CA, vocal fries were often said out loud as a form of subtle hostility toward people perceived as lessers, such as retail and restaurant workers. If you need an example of what I'm talking about, it usually goes something like this:
Poster: "I think (opinion)." 
Redditism enjoyer: "You're wrong?" 
Redditism 3: "Do you need help? Who hurt you? Help is available if you need it, buddy!" 
This one is the worst one I can think of right now because it contaminates even the very possibility of showing sincere care and concern for someone else. It comes loaded with the implication that the person that was "hurt" or "needs help" is fundamentally wrong and should shut up. Fuck that ableist shit, forever. 
I think most of these things ITT are fine when people here do them. the grossness really seems to be associated with the culture of reddit and worse sites.
Sesursoj can have a little repetitive language, as a treat
We can agree to disagree there, though I hope the "who hurt you" social well-poisoning isn't included in your "fine" list at the least.
I was speaking more to the comments, "You're Wrong?" is the only one of yours that has a good utility, redditors just overuse it with false confidence so it doesn't land.
but responding to something that's very verbosely incorrect with a terse correction like that can be very funny
It may just be a subjective thing for me; deliberately-used vocal fry tactics were exhaustively common throughout the years where I worked multiple minimum wage jobs to pay my way through college and having to hear that verbally intoned not-question question mark at the end of a hostile condescending statement for the hundredth time ("Check the backroom agaaaaain?" "Um... Managemeeeent?" "Customer is always riiiiiight?" "Your coworker would be cute if she kept her mouth shut and lost a few poooooounds?" and that last one still boils my blood remembering it).
Maybe, but I'm sure it was also fun/funny to the people I mentioned above that were tormenting kids that were just trying to survive, too.
Agreed. This thread has happened before and it's mostly arbitrary ways to say things that have nothing to do with Reddit.