First thing I thought of was the sound styrofoam makes when you rub it together. But, I also really dislike the sound of people talking when I just woke up. I'm not very into mornings, haha.
Eating with mouth open and sniffing and the two I hate more than anything. Any time I hear someone sniff it sends memories of being sat in an exam hall trying to concentrate and having someone sniff the entire time and distracting me.
I can't stand the sound of children crying, specifically when they are throwing a tantrum in the store or something and their parent(s) aren't doing anything to calm them.