My bag of choice is the
instrument case! Not that I play any instruments, but I find that it is a great conversation piece and the hard back is excellent for protecting my goods:
1. Pie -- Every party thinks cake is the dessert of choice, but honestly pie is at least 3.14159 times better! A warm, fragrant dessert is a quick way to make friends.
2. Life ring -- this doubles as a flotation device for when someone inevitably falls in the pool, as well as a useful prop for party games that involve drowning simulations or attempts to lasso other guests.
3. Lifeguard chair -- I am forever short, so when the crowd is too obtrusive, I have my trusty lifeguard chair to provide a better vantage point.
4. Coin -- not just any coin, but one that disappears and reappears upon touch! I like to pull this one out for magic tricks or to pay off rude / annoying guests to leave. Also entertaining for small children and woodland creatures (or both!)
5. Megaphone -- this isn't so much for me but for the guest of honor. Sometimes they can't be heard over the din, so I like to offer a little help.