People finishing/joining in on the last part of your sentences. I don't think I'll be able to explain what I mean very well, it mainly happens when you're trying to make a point or you're feeling emotive. I don't know whether they are just trying to assure you they agree but I find it so annoying. I try and make the end of my sentences different as to how I was originally going to say it but they still do it! Sometimes I even see their lips moving as I'm talking waiting to copy what I'm saying. I realise I'm not explaining this very well but hopefully at least one person understands lol. I worked with only one other person today in close proximity who did this all day so much so that I eventually just stayed silent and went on MN instead