Well, as Faithful Reader Jean points out, there are real issues with guys hearing about sex from their dads...though, I suspect it's all for show with the sons. From my own experience, I would've liked my dad to have told me as much as he possibly could about things. And, maybe I would've felt embarrassed at first - but that should also be part of a father's job: to explain there is no reason to be ashamed or embarrassed by such a natural and basic thing.
Good heavens, it shouldn't be any more difficult than learning about any other natural function we so easily tackle
And there's certainly no reason to be ashamed of natural curiosity about what is going on and why
Today, with the internet, it's much easier for guys to get access to the info on the proper use of their tools, and self-discovery is nice, and (back in the day) books and magazines helped us
but nothing can take the place of a face-to-face discussion and practical experience.