My children and wife have witnessed me (at various times) putting the cereal box and the phone book in the fridge.
If you’re looking for pure forgetfulness, I once pulled up to Toys-R-Us, dropped off my wife, parked the car, and went in. My wife looked at me and asked, “Where’s the baby?” I had completely forgotten that we had an infant in the car. Luckily, she was only in the car by herself for two minutes or so.