Go to a guest and change his or her name to the following names to give that guest a personality. If you wish to achieve a desired effect with multiple guests, simply enter the same name but change the name's case.
For example, if you wish to have two guests with the name Chris Sawyer, the second guest's name should be CHRIS SAWYER.

Artist Guest - Simon Foster
Fast Go-karts - Damon Hill
Faster Go-Karts - Michael Schumacher
Guest pays 2x Entrance Fee - John Mace
Hungry Guest - Tony Day
Increase Guest Happiness - Melanie Warn
*** Keep doing this to increase your park's rating.
Photographer Guest - Chris Sawyer
Pick Pocket - Richard Tan
Slower Go-Karts - Mr Bean
Waving Guest - Katie Brayshaw
Wow Thinking - John Wardley