James Randi Magnetic Card Lock Story

A few years back I read (or watched?) an article where James Randi told a way-back story where he was in Mexico and hoaxed a groups of journalists - convinced them he could use ordinary playing cards unlock the doors to their hotel rooms which were protected by magnetic card locks. The story was hilarious and insightful - and I would like to share it with some friends. However, I can't seem to find the story on the web.

Can anybody help me?

Thanks.

via International Skeptics Forum http://ift.tt/1Lhdi2u