Not a word or phrase, but I’d ban {or at least shout at} people who post threads asking for specific information or recommendations and then let the thread die without saying thanks: happens more in Care Society and GQ, but it’s damned discourteous. Some things I can answer off the top of my head, other things I’ll look up, or Google to check hunches: I and others are taking time to answer your question when we don’t have to - the least you can do is acknowledge that.
I think that SPOOFE asshole oughta be banned. It’s the only thing that can save the Boards. For reals.
ASSHAT
And “ASSHATTERY”
This phrase isn’t funny anymore. I thought it was used to death among my hipster peers at least as late as last year. No more “asshat.”
“YOU OWE ME A NEW KEYBOARD!”
No one owes you a new keyboard! Every goddamn mildly amusing thing anyone says gets this obnoxious, unfunny reply. It was at best funny enough for a slight smile the first time I saw it. Now, I add names to my list when it appears.
Hear, hear. I too, would like to see a ban on “tinfoil hat”, or at least a concerted effort to Godwinize it. It’s a lazy, ad hominem (umm … personal attack … ) arguing technique that you can almost always leave out of a debate with no loss–just like comparing something to the Nazis/Hitler. Calling Godwin on posters cuts down on the latter laziness, and I’d like to see something similar done to those who slap down “tinfoil hat” labels.
Know what I’d like to see banned from the SDMB? Threads where people complain about catchphrases, in-jokes, and alternate ways of wording sentences. 
Yes, misuse of words like lose/loose and its/it’s bother me too, but not as much as someone coming into a thread just to complain about regional usages of words like anymore and practices like the aforementioned dative shift.
No, I didn’t have to open this thread. I did not have to reply to it. But I chose to because, after all, it is a poll, and presumably the OP wishes to hear from many different viewpoints. So there’s my humble opinion. 
Goat
“and because this is the Pit” string of expletives.
That. I it. Who are you to judge whether or not the bandwidth is being used properly? People pay their subscription fee, they can use the bandwith however they like as long as it doesn’t violate any of the board rules.
People who equate Islam with Terorism.