Boys! Yuck!

What is the deal with a 3 yr old thinking boys are yucky???
Mayra has mentioned that when she goes to the big school (elementary) that she hopes there are not boys there. I'm trying to convince her it won't be the end of the world.
Saturday we had a low key morning at home, and I decided she needed to burn some energy before nap time, so we went to McDonalds. Mom makes faces at me over me letting her eat at McDonalds, but the thing is, Mayra likes it there. Why? I have no idea. She normally will eat at least part of her chicken nuggets, and she seems to like the ambiance of the dining room, even though I usually feel like smashing my head through the closest window when we are there. Sometimes I can convince her to go through the drive through, and we take her happy meal home to eat, but she frequently asks to play on the playground, and I feel bad for blowing her off and saying maybe next time, so Saturday was the day. We ate lunch (if you can call it that) at the restaurant, then she went outside to play.
There was one other girl there when we first went outside. She was a little bigger/older than Mayra but they seemed to be having fun together. the older girl made up a game about running and hiding from boys. It seemed harmless enough when no boys were around, but sure enough eventually a boy about the same size/age as the older girl showed up.
The girls didn't skip a beat, they were running and screaming at the sight of the boy. To his credit the boy was a good sport about it. heck he even seemed to enjoy it, is that good or bad? Unfortunately, at one point he must have made a monster face at Mayra, because she was all the way at the top of the climbing structure and started screaming for Mommy. I had to go part way up to bring her down. She was quite upset, but I will admit it, I bribed her with ice cream. After she polished off a sundae lucky for me she was ready to go home for her nap.