A good alternative is to have a Museum of Working History, the last person being a window washer, and uses a pump spray. No mess.
Cast: Tour Guide, Group of Tourists (optional), 1 Victim, Statues, Aquaman Statue with mouthful of water
Setting: Statue Museum (or Warehouse of Old, Unused Statues)
Guide: Welcome to the museum of Superheroes. We have an unique collection of statues in that you can press a button and the statues come alive to imitate their real life counterparts. See here, for instance. This is Superman. Watch as I push the button on his chest.
Superman comes out of stiff standing position and takes a flying position, then resumes a stiff standing position. Guide continues through the tour, occasionally letting someone try the statues of Spiderman, the Flash, Batman, Wonderwoman, each with a different action and way of activating them (pull arm, press nose, and so on.) Finally they get to Aquaman.
Guide: Now this is our last statue; Aquaman is our pride and joy. However, it seems that sometimes it just won't activate. Better let me try first. (Pulls arm. Nothing. "Aquaman," he whispers. He tries the arm again. Nothing.) (To victim) You, Sir? Would you like to try? He's rather finicky. Maybe he'll work if you try.
Victim tries and Aquaman spits out a mouthful of water at him.