Is it weird that I'm not comfortable with guys rubbing my belly?

Pia
I have a few guy friends that don't bother to ask if they can touch my stomach. They just reach out and try to touch my belly. I smack their hand away and they get upset. Even if they ask I still feel weird about them trying to touch my stomach. My girlfriends ask before they try to touch my stomach. Im not comfortable with guys doing that, unless it's my own father or the father of my child. It makes me feel uncomfortable. Does anyone else feel that way?