Public places like men's restrooms, in airports and train stations, truck stops, university libraries and parks, have long been places where gay and bisexual men, particularly those in the closet, congregate in order to meet for anonymous sex. Over time, people familiar with cruising told, gay men began using a codified system of signals to indicate to others that they were interested in sex. In an effort to curb lewd acts in public - or as some gays argue, in an effort to persecute gay men - undercover police began sting operations in places known for sex soliciting and employed the same codes. 'Tapping of the foot is pretty standard for men who cruise in toilets,' said Keith Griffith, owner of, a Web site on which visitors post locations popular with men looking for anonymous sex. 'They will usually go to the stall at the far end of the strip of toilets. They will see each other and usually decide to go someplace else.