If you weren't allowed to mention the fact that you have one, then nobody would ever be able to apply for a government contracted job. What the government does

If you weren't allowed to mention the fact that you have one, then nobody would ever be able to apply for a government contracted job. What the government doesn't want is people going out to a club and getting hammered and then telling a bunch of strangers that you have a clearance because it makes you a target in a situation where you are already vulnerable. The funny thing is, a clearance doesn't give you a need to know. From my experience the overwhelming majority of people with a Top Secret clearance don't have access to anything that is even remotely interesting.