A few years ago, vacationing families driving down Interstate 75 toward Orlando could see, among signs for gas stations and Waffle House, a billboard with a message.

Waiting just ahead of the Florida Turnpike, it read, “FREE WORLD NOT SLAVEWORLD: END WHALE CAPTIVITY.” The phrase is strange, as if it’s supposed to rhyme. But it makes some sense when you realize “SLAVEWORLD” is a substitute for “SeaWorld.”