Quote by _mal_
Not really a phrase, but still something that irks me...
"that that"
Technically, it's correct in English (I suppose... I don't know of anything that says it's incorrect) but it always makes my mind stumble over the sentence (and mouth, if I read aloud). I usually have to backtrack and reread the sentence to make sure it's correct or that the person hasn't made a typo or some other grammar error.
It happens to me very occasionally and I always rewrite the sentence. I wish others would do the same.
It's a weird thing. We find ourselves writing it but logically we know a "that that" isn't necessary -- we can say the same thing using one "that" or none at all. I say axe it.