A while back my children were playing in their fort when an acorn fell out of the tree and landed nearby.  They were all excited about this.  So I decided to have some fun and picked up a couple of acorns and when they weren’t looking I’d threw them towards the fort.  They were chasing after them and having a discussion on how all these acorns were falling out of the tree, was a squirrel doing it?  They then started to go around the yard to collect more acorns as I continued to toss them in their general vicinity and this keep up for about 15 minutes.  Finally one of them caught me in the act of throwing them; it was fun while it lasted.