I decorated some ornaments and each one had its own word saying "Baby Jensen due 8/22/14". Our parents loved it. For siblings we gave them all baby bottle pops and told them to think about it haha. We announced to our family yesterday we are expecting our second by passing out theses really cute Thanksgiving announcement cards. We couldn't make it to either sides Thanksgiving so one of my sisters and sister in laws passed them out for us and we skyped as they opened the cards. It was really fun.
You could wrap up a big box to yourself with balloons in it announcing the baby. If you will know the sex by then you could put "it's a ....." balloons in it. Put from santa and sneak it in.
You could wrap up a present 'for yourself' and claim you don't know where it's from etc and it be a babygrow or something like it, if there's your family round you announce it that way
*dear, my autocorrect must really hate santa lol
That was supposed to say dead santa!
My aunt and uncle announced their second on Christmas by writing up a Christmas list from their already born daughter saying "dead santa, for Christmas I want a baby doll, a soccer ball and a baby brother or sister" and then told us that she was getting everything on the list. I thought it was pretty cute :)