Why do boys hit on girls unprovoked?

Do any boys have any explanation as to why boys hit on girls who aren’t even interested or just unprovoked?

I was out and about in my city centre around 7pm with my friends, and some dude walks by me and just whispers gorgeous in my ear??? i honestly don’t know what he expected from it? for me to run to him and embrace him? for us to get in a relationship based of the encounter? just plain stupid is it like an aderaline rush? or some sort of ego booster?

I would love to know what goes on in their heads?

edit: i worded my original post wrongly and it has caused a bit of confusion. the better word is catcalling.

i have no issues with guys who approach girls trying to get to know them because they like them, just to clear somethings up