Parks And Recreation: 15 Incredibly Subtle Jokes And Easter Eggs You Probably Missed

Ben is notorious for getting really obsessive, often over things nobody else appreciates. At the Unity Concert, the highlight for everyone is the Li'l Sebastian hologram, but what has Ben excited is the appearance of Letters To Cleo. They perform a song and Ben looks on from the side of the stage while smiling, nodding his head, singing along, and then screaming, "I love you, Kay Hanley!" It's probably the most excited about anything Ben has ever been in the whole series. His apparent obsession with Letters To Cleo is pretty random, isn't it? Actually, it's not that random after all. 

All the way back in Season 4, two years earlier, there's an episode where Ben is unemployed and starts making claymation at home. All through the episode he wears a Letters To Cleo shirt, and so Ben fangirling over them is actually the payoff to an unspoken gag about the specific shirt a character wore one time. Now that's attention to detail.