A frying pan was an utensil used in the preparation of certain foods, where the food is cooked ("fried") in it.
Julian Bashir recalled once a story about Davy Crockett arranging tin frying pans in such a way as to allow the bullet to ricochet off each one in turn. This prompted Miles O'Brien's revelation about displaced targeting. (DS9: "Field of Fire")
Aboard the USS Voyager, Neelix used a frying pan quite frequently when preparing fried foods. In an illusion experienced by The Doctor in 2371, Neelix used a frying pan to knock out a Kazon soldier who had boarded the ship. He was also unhappy when the frying pan was dented. (VOY: "Projections")
After being abused by Seska's version of The Doctor in the Insurrection Alpha holodeck program, Tom Paris jokingly suggested to Tuvok that they next go to the mess hall and let the holographic Neelix burn them with frying pans. (VOY: "Worst Case Scenario")