As narrator Dean says, "Cory was probably the only kid in the world who could make a pick-up line about Pluto work" most likely refers to Dulé Hill's character, Gus, from Psych, whose pick-up line was, "You hear about Pluto? That's messed up, right?"
One of the boys at the Lads and Ladies party says Dean has "memorized the name of all eight planets." Although, during the show's time setting, the world believed that nine planets existed. Pluto, formerly the 9th planet, was reclassified years later and is no longer considered a planet. Perhaps claiming nine planets in the show dialogue would confuse some people but is inaccurate for the era.