It's definitely one stereotype I dislike. Two of my sisters boyfriends were like that with her son, very playful with him. It just shows a guy likes kids, or that he's possibly a family man. But yeah I act like that with my nephew, I usually get smiles because I think I'm read as an older brother since I'm too young and two boyish looking to be his mom. I don't do well with other peoples kids though, they kinda bug me. Babies though are adorable but I don't fawn over them. Still I think it's stupid some people think that makes a guy less of a man. Women are not the only people in this world with a love for children. In fact I've met a lot of guys who are playful like that around kids. The ones who aren't are usually frowned upon by women. Though not all since women can be the same way and completely avoid or show no desire for little kids. It's not a man or a woman thing, it's a human thing. Some people like kids, some people LOVE kids, some people dislike kids, other people HATE kids. Nothing to do with women or men. That guy was an ->-bleeped-<-.
But I have heard the same, "And you want to be a male/man" followed by the fact that I like tight clothing (or did) or that sometimes I like wearing eye liner or because I talk baby to animals. But the way I see it, I know men who have done all those things, so the guys who are saying that probably just have some insecurity with their masculinity.