What this will do is to allow the existing communication pattern to be accepted as a norm and it will be extremely difficult to change in the future. Instead, with a little explicit pushback the OP can express his confusion/dismay at other dude's behavior, set the boundaries and nip this in the bud. Literally, just interrupt him mid-sentence and say - Listen, something's been bothering me. I really don't understand why you are talking down to me. I don't like it and I find it inappropriate.
But as others have said, you clearly have a communication problem, because you both think the other one is an idiot :)
A lot of dickheads are that way only if they are allowed to run around unchecked. Nodding and smiling at them is like feeding the trolls, not the best option.
Given the circumstances -- OP being new to the company and the other person being "friend of manager" -- I would say it would be really difficult for OP to pull off a push back. The advice to put your head down and smile can work wonders when used at right occasion (which I feel like this is one).
Right on! I'd say try your best to let ego issues pass by and just do your part of the job. His behaviour, however inappropriate, doesn't have to affect you.
What this will do is to allow the existing communication pattern to be accepted as a norm and it will be extremely difficult to change in the future. Instead, with a little explicit pushback the OP can express his confusion/dismay at other dude's behavior, set the boundaries and nip this in the bud. Literally, just interrupt him mid-sentence and say - Listen, something's been bothering me. I really don't understand why you are talking down to me. I don't like it and I find it inappropriate.
But as others have said, you clearly have a communication problem, because you both think the other one is an idiot :)