学霸和学渣生了一个学屌
[xué bà hé xué zhā shēng le yī gè xué diăo]
A humorous way to say that the combination of an overachiever (a straight-A student) and a underachiever (often seen as lazy or careless) results in someone who acts obnoxiously intelligent but doesn't really perform well—a 'show-off.'