My parents made a big deal every Christmas about hiding our presents, and forbade my siblings and I from going into a (locked) basement closet during the month of December. That tiny room was the focus of our curiosity, and we never bothered to look anywhere else for the presents.
Turns out they never hid any presents in there. I use the same approach in other contexts all the time.
My brothers and I would have doped that ruse out in about 30 seconds. We learned honesty by being taught how people deceive.