Tijuana, or TJ, as its affectionately - and not so affectionately - known is the Mexican border city south of San Diego California. The dirty city caters to tourists - especially those wanting things illegal or hard to get in the U.S. (such as prescription drugs, guns, and alcohol). There are a number of shops, many of which offer the same things, so make sure to shop around if something catches your eye - and don't be afraid to bargain!