Premature Congratulations

Someone from an opposition company just rang up to congratulate me because he heard 'on the grapevine' that I'm pregnant and about to give birth!!!! What the...?! This is news to me since I'm not pregnant and as such NOT ABOUT TO GIVE BIRTH!

I didn't speak to him directly, so I'm not sure what kind of messed up grapevine he got this info from, but I'm very tempted to call him back and yell down the phone 'Are you calling me fat?!!!' Just to see what reaction I get. I think he would be so horrified that he would forget that we've never actually met in person so there's no way he could possibly have anything to say about how I look.