The grankids are over here often enough that I can make sure they are properly entertained. The other day, my second son and his little one were standing in the front yard and I took little-bit and put him in the bed of the pickup. He though that was the coolest thing ever. He could crawl around, pull up on the sides, play peekaboo, and generally amuse himself while Dad and I leaned on the side of the truck and talked.
My son noticed the fun the kid was having, and reflected that maybe he should clean out the bed of his pickup. After looking in the back of his truck, I concur.