Jack is going to be a big brother

I know I just found out yesterday... But I really wanted to tell my parents our news. I didn't know the right time to say it or the right thing to say. After our Father's Day dinner we were all in the living room and Jack was playing. I just blurted out "Jack is going to be a big brother!" Blank stares... My mom says "What are you saying?" I repeat myself. She just gets this really weird look on her face, actually several looks. My dad tells us congratulations. He said he thought something was up when I wouldn't drink wine at dinner. They ask if I told my brother earlier when I talked to him. I say no, I was going to tell them first. My mom asks me to call him now because she wants to know how he reacts.
On the phone with Alex. I tell him "Jack is going to be a big brother!" He says "WHAT!" Then he says "How do you know it's a boy already?" I start laughing, I say "We don't know yet, it doesn't matter if the baby is a boy or girl... JACK will still be the big brother!" Then he realizes what he said and we all start laughing.