Concert security in those days, especially for heavy metal events, was pretty tight so it was no surprise that they were patting us down pretty good. Now Mark in those days was big on recording live events and trading "bootlegs", so of course he had a recording device that he needed to conceal; and where do you think he concealed it?
In a word, crotch! He shoved the darn thing down his pants and hoped for the best. In the eighties, we relied on analog cassette tapes, so the recording devices were considerable larger and more squared off in those days. As a result, the recording device left a boxy bulge in Marks Levi's and this got the security staff
Have you any clue how freakin' hard it is to keep a straight face through this? While we were holding back the laughter, Mark thought quick and told Mr. Touchy/Feely Security guy that he had just had an operation and that the hard item in his crotchety region was a cast. He let us through, we saw the show, Marc recorded it happily ever after. Nothing more need be said.