I was almost through the security checkpoint at Baltimore-Washington International last week when a TSA agent flagged my duffel bag for further investigation. The offending duffel bag, it turns out, was filled with wrapped Christmas gifts for my family. And the offending item was an 8-ounce jar of only vaguely liquiform pesto I’d brought for my cousin — promptly confiscated and thrown into whatever bin the TSA keeps these things.

This type of incident is not uncommon around the holidays, despite TSA’s many attempts to educate travelers on what gifts are and aren't acceptable to carry on a plane. But the rules can be … counterintuitive. Like you can bring 3.4 ounces of olive oil on a plane. But an 8-ounce jar of herbs, with maybe 2 ounces of olive oil, crosses the line.

Here, for the record, is TSA’s full list of holiday items you cannot put in your carry-on (in addition to the standard explosives, weapons, etc.):

  • Liquids over 3.4 ounces, including cranberry sauce, cologne, gravy and sauces, jams, jellies and “creamy dips and spreads,” including peanut butter
  • Snow globes larger than a tennis ball. Snow globes about the size of a tennis ball or smaller can go in your carry-on if you bag it with your other small liquids.
  • Hockey and lacrosse sticks, baseball bats and ski poles, including the toy varieties
  • Toy guns or anything else that looks like a weapon
  • All tools longer than seven inches, and all knives of any size
  • Gel candles (like these ones)

Baked goods and foods are allowed, but subject to additional screening. And pesto, clearly, is out.

For a full list of what you can or can’t bring on the plane, consult TSA's mobile app.