Good video on what happens during a CBP random checkpoint. Note how many times the guy filming asks if he is being detained before the CBP finally allows him to carry on without him ever answering CBP agent's question. I wouldn't do this if you weren't a US citizen. 
http://www.youtube.com/watch?v=u6uw7506xMw
http://www.youtube.com/watch?v=u6uw7506xMw
Last edited by a moderator: