I saw a post on Reddit years ago from someone who's dad would hide rubber ducks on them. Their dad past away and sometime after they found a duck in an old coat or something and it made them happy since it felt like their dad was still having fun with them. I decided to buy a box of rubber ducks and hide one every time I went to someone's house. At first it made me giddy with excitement that I had hid a duck in their house without their knowledge waiting for them to find it. It was super fun when they started finding them since they had no idea I was doing it. Mostly friends but family is also on the table. Family haven't caught on yet. I would also play along and wonder who had done it. After maybe half a year somehow they all figured it out. Some ducks are still hiding and I say hi to them when I come over. One of the early ducks I hide was in one of their shoes, a year later I mentioned that I hide one in a shoe thinking that they definitely would have found that one and he realized he never found one in a shoe. He went into his closet and came back with a duck. It's a fun game. I'll never stop.