Know I mention Disney but this is about amusement parks in general so I'm putting it here.
One of my favorite things to do at Amusement Parks is to add to the illusions for other guests. Some of my best moments:
On Splash Mountain, most people reassure scared kids. But to be honest the "kid" (looked more like 15) looked old enough to take it, so instead I "reassured" him, actually making the ride scarier. "It's okay", I said. "The survival rate on the ride is surprisingly high. Actually higher than ten percent, I think." Then, since I was on her log, I whispered "We're not gonna make it" shortly before the final drop, followed by shouting "WE'RE NOT GONNA MAKE IT!" during the final drop.
On It's A Small World at WDW, I waved for about fifteen minutes in a constant rhythym at that one window overlooking the start of the ride. This one family smiled and waved back. I'd like to think that someone mistook me for the first animatronic, wishing the boats well as they start the happiest cruise to sail the seven seas.
While in the queue for Space Mountain, I recounted a conspiracy-esque story, in vague terms, to anyone who would listen, about how Space Mountain is actually a secret project by the Disney Corporation to let aliens visit our planet for various (benevolent) purposes in secret. Disguised as humans, they use the ride as their entrance and exit to Earth, teleporting into the ride as it ran. A group of small girls actually believed me and felt brave for braving Space Mountain no matter what types of aliens went there.
I ALWAYS look incredulously at people who ignore the "WARNING DONT DO THIS" signs in the Indiana Jones Adventure, asking them if they're suicidal or just completely oblivious, pointing at the signs.