Rumour has it

Just before Owen turned 1 and had started walking, Josh decided that he was no longer a baby and therefore, it was time to have another baby.  This was the conversation: 'mommy, since Owen isn't a baby anymore, we should have another baby.  I want a baby sister and I need another player for my basketball team.  Oh, and when she's not a baby anymore, we can have another one and then another one'. So, is this how the family on TLC has 19 kids?  My response was 'I agree, we should have another baby but you will have to talk to daddy!'. 
What I thought would be over with that one conversation, has been an obsession ever since.  Atleast once a week, Josh asks me when is he going to have a baby sister. The other week, he asked me when I was going to grow a baby in my tummy.  I told him not for a while and he said 'oh, so by Christmas, will I have a baby sister?'.  Mmm, maybe next Christmas?  He actually wants lots of baby sisters and told me that he would help me take care of them and showed me how he was going to rearrange the furniture in the living room to fit all of their cribs.  He is also going to teach Owen how to change diapers so that he can help.  Wait a minute, if Josh knows how to change diapers, I should be getting him to change Owen's.
The other week when at a completely random time, he told me he wanted a baby sister, I asked him that if we do decide to have another baby, what if it isn't a girl?  His response was 'no, it has to be a girl because I want a baby sister. I want lots and lots of baby sisters'.  Oh yeah, and last week, he told Mike that he is going to name her Sophia.
So, it seems like a very cute story but here is where the trouble lies.  Since Josh thinks that one day he is going to have a baby sister, he has started telling people that 'I am going to have a baby sister'.  A few weeks ago, his teacher told me that Josh told her that he is having a baby sister.  No, I am not pregnant.  Last week when skyping with Grandma, he told her that he is going to have a baby sister.  No, I am not pregnant.
So, if people start asking me when I am due, I'll try not to be offended.  I will just assume that my 3 year old told them that he is going to have a baby sister.