Activity for LaVonne

I had purchased a pair of shoes I loved two weeks ago but when they arrived the ankle strap was too small. Then I found these and I'm sooo glad the other's didn't fit. I'm in LOVE

I'm having a themed wedding and would like to encourage guests to wear "dress hats" for the occassion. I'm stumped on the wording. Oh and we are not "traditional" so they whole traditional "your presence is required" is out for me. Any suggestions?...