I asked in all of my first supervisions (unless there have been emails, which is more regular since I've been sorting out my own supervisions). My favourite was "shall I call you Rohan, or Dr Stewart-McDonald?"(Original post by sTe\/o)
Yeah, you'd think that'd be a good idea, wouldn't you? And yet I asked one of my supervisors this in the first year when I met him for the first time and he was just flabberghasted. Apparently I was the first person ever to ask that question, a point he brought up in almost every supervision for the rest of the year, since he reckoned it was quite a funny story.
What are the downsides?