Try Ana's smart hack on your next summer outing:
At the zoo, it was extremely hot and humid so I pulled out the water bottles we brought to keep hydrated. Within seconds, the cold bottles, of course, started dripping condensation and it was hard for our three-year-old to keep a grip on his. Having a pre-schooler, I always pack an extra set of clothes so I reached in the bag and pulled out one of his extra ankle socks and slipped the bottle in it through the opening in the sock. It fit perfectly (he wears a size 8 toddler shoe), and it continued to soak up any condensation until he was through with the water. I've tried using napkins before to do the same thing, but always ended up with bits of napkins everywhere (three-year-olds will pick at anything they can pull apart) and they don't always fit all the way around the bottle depending on the size of the bottle. The sock was a perfect fit, and our son thought it was funny that his bottle of water was wearing a sock!