Easter eggs from the movies and books are hidden throughout the park for the curious muggle willing to find them.
In Zonkos Joke Shop, you can hear whispering coming from Extendable Ears hanging over the register
If you want to take some home with you they are for sale in the shop. Along with screaming yo-yo's, a decoy detonator, and nose biting teacups
Via bakingdom.com
There is even a sign warning you of their eavesdropping
Even though technically it's the ceiling that has ears...
Via mugglenet.com
Also in Zonko's, you can adopt your very own Pygmy Puff. When you do, the attendent will ring a bell and announce the name of your Pygmy Puff to the whole store!
Via wizardingworldharrypotter.com
There is also evidence that you can buy suction cup shoes and, despite that others have clearly tried, they don't like you walking on the walls
Via wizardingworldharrypotter.com