Allows you to spin crank and rear wheel!
All you need is a hammer, 2 nails and a wood post. Use real manly sized nails; brads and finishing nails won't cut it.!
I have a post holding up my patio roof. I've used this method on a wooden bench in my basement before. You could probably use a tree too.
Don't use a 'nice' post. Your wife, roommate, landlord etc. will get mad at you!
Angle the nails up so a 'V' is formed by the nail and the post. The rear chainstays go in the 'V'.
It may help to lay your bike on the post first to see where the nails would go.