Stop touching my belly!!!

M • Mommy to the cutest 2yo boy! Now we have twins on the way!
I was at the supermarket today and while looking over my shoulder to look down an aisle and woman came over and started rubbing me. She says "oh, honey, you look fantastic". I walked a quick two steps back to get out of her reach. I don't get it!! WHY ARE YOU TOUCHING ME?!?!? 
Just yesterday my friend and I took our two year olds out for dinner. The tables on either side of us couldn't stop staring. I understand they were happy for us because are both pregnant and had our kids but.... seriously?!? They kept commenting and smiling the whole time. First they wanted to know how old they were... then how far along we are.... then what apps do they watch on our phone while eating dinner... blah blah blah
I find myself to be a friendly person but some people really cross the line. I will have a small conversation but I think I should be left alone after that.