Shortly before AirVenture I walked into my hangar, only to find a blue stain under the right wing tank. I keep a spare quick-drain sump plug on hand for just such occasions. After seven years of flying, that occasion finally raised its head.
I placed a clean bucket under the offending leak. I then removed the faulty drain and inserted the spare without losing too much fuel.
The question I struggled with was how to hold the quick-drain plug open while I changed the mini O-ring. A quick tour of my shop/hangar had me grabbing my trusty Cleco pliers. They turned out to be the correct size to hold the drain plug open, while I changed the O-ring. If you need two hands to install the O-ring, you can use rubber bands or safety wire to hold the Cleco pliers compressed.