Costume Class coming up... costume help?

I like the mermaid, because I think it would be hard to decorate your horse as bullseye and I dunno about coconuts. Take her blue blanket and tape cutouts of fish and starfish on it. Do you have a side saddle? You could be an octopus instead, perhaps. I would also like the Hawian theme,but I think yo would need a little more to cover up than just a coconut bra. I can see that ending badly.