All this talk about the Grey's Anatomy/Private Practice crossover event (which ends this week) has got us at TWoP thinking: true television crossovers are rare. They are not merely spin-offs (though they often involve characters from a spin-off), and they require more than just a mere mention of something from one show on another -- actual characters from both realities must interact. For ease in production, crossovers often happen between shows on the same network -- usually between shows from the same creator -- but occasionally they occur between shows that have seemingly nothing to do with each other. So what are the best examples of this elusive and mysterious breed of television event? Here are seven that we feel stand out from the annals of character-jumping television history.
Jim and Pam are having a baby this week on The Office and, unfortunately that's been one of those TV conventions that tends to send shows on a downward spiral. The Office has already barely survived the marriage of two leads (another frequent show killer), so to now add a baby to the mix is just asking for shark-jumping trouble. While a drama like Friday Night Lights, which is built around familial struggles, or a series like Friends, where characters mostly forget about their kids, can sustain their quality levels postpartum, plenty of other programs haven't fared as well after the stork dropped off its little bundle (or two) of joy. Here's a look back at some of the unwelcome arrivals that put a damper on once-successful shows.