is it really socially acceptable to approach a stranger in public and comment on the size of their stomach? and if so…

is it really socially acceptable to approach a stranger in public and comment on the size of their stomach? and if so why get angry when I follow it with a comment on the size of your ass?! I didn't ask you to tell me how I looked like I was ready to pop....I am only 8mo along and I can assure you I was MUCH larger this far along with my first than I am right now! I just don't understand people!