Suggestions for a Rock-a-billy/pin-up style baby shower

Me and my sister-in-law are putting together a good friend's baby shower. She doesn't want the typical shower. It's going to be co-ed and she wants it to be themed like Rock-a-billy or Pin-Up Style. It's going to be "dress up recommended." I can't find any thing with those themes. I think we are going to serve hamburgers, hot dogs, and milkshakes to go with the theme, but I'm up for any better suggestions. The men are going to play poker and half of the winnings will go to the baby fund. She's doing a pregnant photo shoot that is going to be pin-up style and I think we are going to use the pics for the invitations, but I can't find any templates that would fit the theme. Any suggestions on where I can find decorations, food ideas, invitations, etc. etc.