MustAdministerSteroids and Jguns are doing it correctly. All you other bro's need to do the right thing and get rid of 'em properly. This is not a trivial issue.
I usually put them in a Wal-Mart bag and throw them out the window of my car when I'm passing the homeless drug addicts on the street. They are pretty appreciative of slightly used needles. Sometimes they even spit at me.