And Then There Were No Delinquents

is episode 52 of the Beelzebub anime.

Summary
It's a snow day, and Oga and the rest of the Ishiyama delinquents show up for class to find no one is there. Kazuya and Azusa appear to help them, but when they find delinquents getting beat up, Kazuya suspects it's the song where the Holy Knights beat up delinquents.

Trivia

 * The title of the episode is based off the title of the British novel.
 * The "100 Delinquents" counting song is also based off "10 Little Injuns", the original version of the nursery rhyme Ten Little Indians.
 * The expression that Furuichi mentions in relation to Shimokawa writing "good naito" on the bathroom stall is, a possible allusion to Japanese professional boxer Daisuke Naito.
 * When Takeshi Shiroyama was incapacitated and then left naked in the nurses office with the love letter according to the song, Furuichi remarks "That's a big love letter..." implying he was possibly referencing to Shiroyama's penis.