I don't mind when my family members touch, but it strangers start reaching towards my belly, I will seriously jump away. I also HATE when I'm lying down and my husband puts a lot of pressure on my belly. Sometimes he wants to rest his head on there... I keep telling him there's nothing to hear, or sometimes it's just his arm around me but too much weight on my stomach. NOT comfortable.
PS, if it were a stranger, I would just politely ask them to not touch me. I don't think that's any more rude than reaching out and touching a stranger!