IN BRIEF: something for nothing; an easy time; taking part in something without contributing anything.
NOTE: Someone that wants it easy all the time is only out for a free ride.
When Marijuana smokers are smoking together they tend to pass the Marijuana Joints in a circle. To make it fair they usually take the same amount of Tokes, if they don't then they are Free Riding...just taking as much smoke as they can before they pass it on.
Dave: Is it a Free Ride?
Ben: Yes, I've been Free Riding.