When I'll get my BFP, I'm planning not tell anyone (just parents) until we find out the gender. Then I'll just tell everyone "hei, we are having a baby G or B"...so I can only get the "Congrats" and end of story.
Those people laugh but it's not their laugh. They can't understand what is in your soul and that's probably why they act like this..but if you decide to tell everyone before finding out, just tell them you are having another girl and if it's a boy, then WOW for everyone.