Food Poisoning (Staphylococcus aureus or Bacillus cereus): This is the most likely diagnosis given the short incubation period and the duration of symptoms. Staphylococcus aureus and Bacillus cereus can produce toxins that cause rapid onset of watery diarrhea after consuming contaminated food, such as chicken salad.

Viral Gastroenteritis: Although the incubation period might be slightly longer than the time frame provided, viral gastroenteritis could still be a consideration, especially if the chicken salad was contaminated with a virus like norovirus.
Salmonella or Campylobacter Infection: These bacterial infections can cause diarrhea after consuming contaminated poultry products. However, the symptoms typically last longer than 3 hours.

Botulism: Although rare, botulism is a potentially life-threatening condition that can be caused by consuming contaminated food. Early symptoms include gastrointestinal issues like diarrhea, which could initially be mistaken for food poisoning.
Clostridium perfringens Food Poisoning: This bacterium can produce toxins that cause diarrhea and abdominal cramps. While not typically fatal, it can lead to severe dehydration if not properly managed.

Vibrio Infection: If the chicken salad contained seafood that was contaminated with Vibrio species, this could be a rare cause of the symptoms. Vibrio infections are more commonly associated with consuming raw or undercooked seafood.
Giardiasis: This parasitic infection can cause watery diarrhea but usually has a longer incubation period and duration of symptoms. It's less likely to be related to the consumption of chicken salad unless the food was contaminated with the parasite.