As I've always said, locks are for honest people. This is a simple lock to thwart the common bike snatching. I also tend to ride old bikes worth less than a Kriptonite so, this works for me.
Step 1: Chain & S-link
I had an old chain with this "S-link" on it. I attached the link to the break cable stay that is no longer used.
Step 2: Lock It Up
This is just on my bike stand. I usually lock to a shopping cart, BBQ, garden tractor, or what ever my be by the exit in plain sight.
Step 3: Lock Up Your Friends
If I stack them I can comfortably lock up to 4 bikes. Picture me rolling :)
Step 4: Sleeve It With a Bike Tube
I get a tube in proportion to my link size. I use a string and soap to pull it all together.