This was not on a commercial flight but it was along the same line. I was on a Canadian Forces DeHavilland Dash-8 traveling across Canada. The crew was all military (US and Canadian Forces) and we were all wearing flight suits (easy to clean nomex). The Flight Steward prepared (actually cooked vice reheated) homemade meals. One meal began with his grandmother's recipe for borscht. As he headed down the aisle to serve we hit turbulence. He dumped the entire tray (probably 6 servings) of soup entirely on me. Fortunately, it didn't hurt. The stunned silence broke into laughter when I announced, "Soup's on me, guys!" The steward apologized and the rest of the plane (all co-workers) had endless fun at my expense for the rest of the trip.