John Green. Enough said.

I always do that for some reason and I don't why.

At least yours was grammatically correct aside from that. Our guest, however, should have said "If you HAD used 100% of your brain, you would HAVE USED "their" in that sentence"

They're actually both usable.

While not incorrect in and of itself, you have a conflict of tense. You said "used", being purely past tense, and then later said "would use", which is the condicional placed somewhere between present and future.
The only way to correctly state your point there would be "If you had used 100% of your brain, you would have used "their" in that sentence"
Don't try to grammar with me son.

Used can replace "Were a user of"

And where, pray tell, is that even coming from? You're slightly off-context there bro.

If you were a user of 100% of your brain you would use their in that sentence. Again, used can replace were a user of.

I think you mean "used" can be replaced BY "were a user of".
Again, any and all attempts to grammar with me will be met with complete and utter failure, I'm afraid.

You're still choosing a different way to state an already correct sentence.

Your sentence was using two opposing halves of respectively correct sentences. Separately, with their counterparts, they work just fine. Putting them together may seem aesthetically non-problematic, but it's simply incorrect.

Breaker breaker, come in earth....this is rocket ship 27. Aliens fucked over the carbonateur on engine number 4, I'm gonna' try to re-fuckulate it and land on juniper and hopefully they got some space weed, over.

And here dies my last hope for the guests on this site....

Oh come off of it. I'm a police officer not a linguist. Congratulations on your well deserved victory. Registered users will remember this moment for years to come.

It wasn't your being incorrect that bothered me. It was your inability to accept the fact, and amidst your eminent doom, your choosing to resort to what I can only assume was whatever gibberish happened to be passing your mind at the moment. What I enjoy above all else is an educated argument with someone I can respect, and in entering such discussions, I follow the proper code. In the event that I am proven wrong, I accept my defeat graciously, and expect my opponent to do the same. But it would appear that any semblance of etiquette is beyond rare where it used to be commonplace. And lastly, in my lamenting my dying faith in others, it was your choice to resort to sarcasm, a tool that I see much value in while being facetious, but as a last resort to inflict emotional pain, I can only describe it as childish. I'm sorry if my breaking down this entire thing upsets you in any way, but I simply feel the need to explain myself to the best of my ability in such circumstances.

Perhaps I can learn from your honorable posting methods.

Etiquette in court, yes. Etiquette at dinner, yes. Courtesy, professionalism, always. On Funsubstance.com, I couldn't care less. But I respect your point. You got me. Congrats man.

Thank you so much for saying "I couldn't care less"
So many people say it as "I could care less", which means you do care, at least a little. Not many people know the proper way to say it, so kudos.

We agree on something! That always gets on my nerves. This is a good time to bring our argument of epic proportions to an end. Besides, I'm too afraid to say anything more. I'm in constant fear of another humiliating error.

Agreed. I always prefer to end on a good note. Good day to you, comrade!

Good day!