Send an invitation in a bottle or ice cream container

• Use an empty root beer bottle sent in the mail
  
  Write the information for the party on a paper invitation. Roll up the card and carefully insert it into an empty, dry root beer bottle or ice cream container. Seal the bottle with a cork or screw top. Put the required postage on it and send it through the mail. Use only a plastic bottle to mail, and add a note to the outside of the bottle for the guest to look inside. Hand delivery of glass bottle invitations is the best policy to ensure that the bottle does not break or pose a hazard for the post office. Possible wording for the invitation could be:
  "Where's the root beer? (And ice cream?) You're invited to a root beer float party to find out." (See reference 2)
  
  

Base the invitation on the purpose of the party

• Design a homemade or printable invitation (see Resource) based on the purpose of the party. Some root beer float parties are charity events to support a specific cause or organization. Attach stickers or insert information about the cause such as a brochure with the story of the charity and why the party is supporting it.
  
  

Use a stuffed animal

• Hang the invitation around the neck of a toy cow
  
  Punch two holes at the top of the invitation, and tie either end of the string into the holes. This will create a hanging sign. Hang this around the neck of a toy cow, preferably a black cow. Root beer floats are also known as "black cows," and the toy will be an eye-catching keepsake. If using a plastic toy cow, the invitation could be written directly on the side of the cow with permanent markers (see first Reference).