Princess Eugenie, left, with Princess Beatrice and memorable hat. (Toby Melville/Reuters)

You know the hat. Everyone knows the hat.

Princess Beatrice wore it at the Royal Wedding - showing up all the other stuffy hat-wearers. Kate Middleton would never have worn it. That's one reason I love it. It's simply something to talk about. And laugh about. And blog about.

The hat was designed by professional milliner-to-the-stars Philip Treacy, who was also behind some 35 other hats at the wedding. But this hat was so ridiculously amazing that it's the hat that everyone will remember.

Web citizens have a can-do attitude about who might wear the hat. (Knowyourmeme.com)

So memorable that Buckingham Palace is auctioning the hat on eBay, with proceeds to be donated to UNICEF and Children in Crisis. Happy ending for all.

Meanwhile, the fallopian-tube-toilet-seat-octopus hat is a hot internet meme - inspiring can-do citizens of the world wide web to slap Princess Bea's hat on everyone. Osama. Obama. Kim Jong Il. Gollum.

I love this hat.