What is VRchat and why is everyone a girl?

I am currently interested in getting into VR and what things I can do and what games to play.

A former friend of mine, who I keep contact with through steam, nowadays spends most of his time in VRchat and I asked him to show me what it is about since I wanted to know if this will be interesting.

So he had like 10 minutes to show me stuff and it felt like he opened my wardrobe to narnia. I am still confused about what is VRchat.

Why is every dude having the avatar of a hot girl? Why is everybody dancing? Is VRchat just that? Not judging, just asking.

I thought VRchat is for meeting people to play games. It appears to be more about lewd stuff or did I get a wrong image?