This isn't about cougars chasing after twentysomething guys or college students hooking up with professors. We're talking about relationships between adults and underage teenagers that are actually illegal, among other things. Yet, while they're illicit, ill conceived and dangerous in the real world, we can't get enough of them on scripted TV. Hell, some of them are our favorite small-screen couples of all time. While there is a current rash of hot-for-teacher storylines, there have also been plenty of other underage characters who've fallen for someone far too old for them.