The good people at Oxford have done us the service of compiling the ten most irritating phrases. You can read the article here, but I've done you the service of copying the list because every time I go to the article, my computer hangs for five minutes.
I don't know how much time and money Oxford spent on this study, but they could have done better. Here's their list:
1 - At the end of the day
2 - Fairly unique
3 - I personally
4 - At this moment in time
5 - With all due respect
6 - Absolutely
7 - It's a nightmare
8 - Shouldn't of
9 - 24/7
10 - It's not rocket science
Kudos to #1: at the end of the day. It's not that at the end of the day is all that irritating, but people who use this phrase use it after every freakin sentence.
And #5 is a good. Its variant is "I don't mean to burst your bubble, but..." (don't want to rain on your parade, don't want to be the voice of doom, don't want to be a wet blanket, etc.) Again, it's not the phrase, it's how it is used—in that passive aggressive I-mean-the-opposite-of-what-I-say way: of course I don't respect you and of course I want to burst your bubble. I get off on bursting bubbles, that's what I do, in fact if I can smote your happiness for just one moment, I hate myself just a little bit less.
The other eight phrases, they don't bother me.