Backyard cocktails are great, but if you're not vigilant you may find a fly or wasp in your drink. Placing a cupcake liner over your drink with a hole for a straw will help keep your beverage insect-free.
This tip comes from The Cupcake Blog, and obviously will appeal more if you're a regular baker and keep cupcake liners (or patty cake containers, if you must) on hand. Cupcake liners also come in handy to catch ice block drips. If you like the cupcake theme, the site also has recipes for adult beverage cupcakes.
Cupcake Liner Summer Drink Covers [The Cupcake Blog]