Man Tries to Board Plane With Knife in Mayo But it wasn't a great hiding spot: the TSA considers mayonnaise a gel By Newser Editors and Wire Services Posted Apr 3, 2012 12:33 PM CDT 42 comments Comments What lurks within? (Shutterstock) (Newser) – Score one for the TSA: Security screeners at New York's Kennedy Airport caught a man trying to smuggle a knife onto a flight ... by sticking it in a full tub of mayonnaise. A TSA rep says screeners stopped the man today as he arrived for a trip to Mexico City. The hiding spot was far from a brilliant one: Jars of mayonnaise are also banned from carry-on luggage in the US because the TSA considers mayo to be a liquid or gel. The TSA notes that the man still caught his flight, sans knife and condiment.