I'm a real killjoy, got a feeling that I'm going to enjoy writing this...
Use of the phrase "I wouldn't mind but..." when explaining something that is obviously causing the speaker to mind so much that they are ranting to me about it.
The word "Ta" fullstop, although despise it when toddlers are told to say it in place of "Thank you"
Visitors that spill coffee on my sofa due to their leaving the full cup of coffee on the sofa arm - FFS, why?
Networking
Talking utter bollocks at Committee Meetings, turning the quick 20 minute meeting into another 3 hour one
Being harrassed into digging my allotment - I've paid my annual fee, please leave me alone!
White top, grey bra 
Parents with snotty nosed children who insist that they give my DS a kiss, poor child
Randommers who insist on talking to, and touching my child in the street and on public transport, please leave us alone
Use of the words Xmas, Chillax, Nom nom nom, sik, and "apps"
People unable to say NO to a toddler - you are the parent, they are your child, just say no - it really isn't that hard
They'll be more...