This actually happened about a month ago.
My buddies girlfriend was having a few people over, mostly her friends and none of which knew I carried except my buddy and his girlfriend. Well anyway, I was coming from work and had my gun cable locked under the seat but forgot to stick my holster in the center console as I usually do. So for the night I was carrying without a holster in my waistband. On the drive over the mag release button must have gotten engaged and the mag was sitting half in half out. Everyone was in the kitchen and about a minute or two after getting there the mag fell from the gun and hit the floor. Needless to say everyone noticed and started asking if I had a gun and if they could see it, which I declined. I was kinda embarrassed so I just stuck the mag in my pocket and went into the bathroom a few minutes later to pop it back in. So much for being discreet.