Worked with a front end dev that said "hmmm" to almost everything. She would do it in a way in which she sounded very interested in what you were saying. In one meeting we counted over 100 of them.

That doesn't sound so bad!

It's worse when my doctor says it.

@ChrisCooney I wish you could experience it in person. lol I'm not a picky guy, when it comes to people's personality quirks. I also worked with a constant whistler at that time and it never bothered me.

But that constant "hmmm", every 5 minutes... it killed me.