Security for bike on hitch rack.

Do any of you somehow lock your bikes on the auto bike rack? I wouldn't think they are too safe just hanging there when you are in a store or somewhere unattended. 

I was in Wal Mart today looking for the Allen tention bar to use on bikes that don't have a top tube. When I checked out it was reduced to $7 instead of $16.96 so I got 2 of them. I was happy about that. 



Fran,
 
Be who you are and say what you feel........
Because those that matter dont mind.....
And those that mind don't matter.   Anon