For my daughter's July 25 birthday, we sent out Christmas-themed invitations, and asked guests to dress in red and green.  We had a small decorated artificial Christmas tree and the guests got into the spirit of the day and brought gifts wrapped in Christmas paper.  The cake was decorated with Christmas flowers and we had a Santa Claus piñata, Christmas paper plates and napkins and red and green balloons.  I was able to find unpainted ceramic Christmas ornaments at a craft store, and the kids had a great time painting their very own ornament to take home. We sang a few Christmas carols and passed out candy canes and everyone had a Very Merry Christmas on a beautiful summer day!