Danger, bad advice, this is obviously a SSI TSA plot to entrap Flyertalkers. In the hot summer peanut butter is soft, you are just daring some TSO to confiscate your PBJ as "too gel like." Don't forget peanut butter looks like C4 on the xray, stick your smart card with a chip in a PBJ and "OMG electronics inside explosive, it's an IED, call the bomb squad water cannon to blast this thing!"