The above post made me remember this story ... it wasn't necessarily the strangest thing I ever brought, but maybe the dumbest.

We were flying home from Disneyland and my son had a helium-filled mylar balloon. No one said a peep as we brought it on the plane and it didn't cross our minds that we shouldn't. We stuffed it into an overhead. We're not too many minutes into the flight and there's a very loud boom. I've never seen so many people jump and become extremely aware. Woman across the aisle from me kept saying, "What was that? Was that a bomb?" I couldn't help laughing as I told her what it really was, which didn't exactly endear her to me. I won't bring any helium-filled balloons on airplanes anymore.