There was a time when an air force transport plane was carrying a bunch of military dogs. One of the dogs somehow got loose and managed to get into the cockpit. It started barking at the pilots and trying to 'help' fly the plane. The pilots were both amused and a bit panicked as they tried to get the dog back to the cargo area while still flying the plane safely.
In some funny fire drill stories, the funniest part is often the costumes or items people bring. There was a story where a man came out in his pajamas and a sleeping cap during a fire drill at an apartment building. He looked so out of place among all the formally dressed people. Also, when pets are involved, it can be really humorous. A cat once climbed onto a person's head during a drill because it was scared, and the person just walked around like that until someone noticed and helped.