Well there's many ideas of what makes a man, but I think they can be categorized as; the societal views of a man and what a man actually is. A lot of the ideals of a man are just stereotypes and "normals" of society. Basically it's a bunch of ideas that are widely agreed upon which give these beliefs a weight on the individual to accept it as a truth, which in many cases it's not.
Liking sports is a stereotype of a man, same with sex. Peeing standing up is just something we do because we can, and having a penis is just a part of being a man.
This is definitely a good topic to bring up because I often wonder about this as well.
"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein