If you're cooking the meal but also want some help in the kitchen, there are ways to turn your request for assistance into a fun challenge. For example, have your guests compete to see who can chop vegetables or grate cheese the fastest. Award points for style; take away points for making a mess (and be sure to use sharp knives to lessen the chance of injury).
Another good challenge is the saucepan flip. If crepes, pancakes, omelets or something sauteed is on the menu, test your chefs on their ability to do a smooth flip. Of course, this has the potential to end with food everywhere but the plate, so be sure to have extra ingredients on hand, or lower the stakes a bit by having participants try with something like bread cubes in a cool pan.
If your guests can chop, grate and flip like pros, see how long they can keep their cool during the next challenge.