From botched mugging to unlikely love. Songs You Know by Heart When David was younger, he spent a lot of Saturday nights on his knees: in alleys, in men's rooms, occasionally behind a hedge in Central Park. He liked it rough and he still does, but he tries to be safer about his choice of partners and locations these days.He didn't expect an attempted mugging to be the cause of his relapse. The guy shoves him up against a tree and puts a knife to his...