Ideas on pregnancy reveal for soon-to-be grandparents?

My parents have been dying to be grandparents for a while now. My eldest brother hasn't been able to conceive with his wife since they started trying years ago. Now all my mom's friends are grandmas and she won't stop complaining about being the only one that isn't! Lol. I'm the youngest of 5. 4 older brothers and the only girl. Yes. It's been great lol. Anyway, I just found out I'm pregnant and I really wanted to do something special for them to announce that they finally get to call themselves grandparents!! How did you guys do it??