Baby Shower Help!

Alicia
My mom and sister are throwing me a small, traditional baby shower for family. 
My husband and I are throwing ourselves a larger BBQ type party and inviting all of our friends to just hangout and play yard games and eat before we have a baby. It's not a shower, but I know many of our friends would like to give us gifts, since they will not be attending the actual shower. I want to include our registry info in case people want to bring a gift, but I don't want people to think that it's necessary or expected!
What's the least tacky way to handle this? The BBQ will just be a Facebook invite, not a formal mailed invitation, as it's not meant to be a formal thing.