Rename one of the tourists to have the desired effect:
"Frontier" - Buildings never break.
"Guido Fawkes - Gives access to advanced fireworks.
"Atari" - All visitors burst out laughing.
"Chris Sawyer" Visitors to jump for joy.
"John Wardley - Removes height restrictions for buildings.
"Andrew Gillett - Increase the value of the park.
"Atitech" - The people run for 20 seconds.
"Atomic" - Explosions.
"PhotoStory - People take pictures of the park.
"A Hitchcock - Pops up the ducks.