盗人猛猛しい
(Nusubito takedakeshii; “An impudent thief”)

Definition:

Remaining calm and self-assured even when doing something wrong. Alternately, when you get caught doing something wrong, acting defiant or even becoming aggressive toward the person who caught you, instead of being properly embarrassed or contrite. Brazening out your own crimes and wrongdoings. Evil chutzpah. Currently, acting presidential.

Breakdown:

This simple subject-predicate phrase begins with compound noun 盗人 (nusubito, although see below), “thief” or “robber.” We can imagine an elided topic marker here, but what we actually get is a comment in the form of adjective 猛猛しい (takedakeshii), “shameless,” “bold,” “ferocious,” in modern conclusive form but with any sort of copula elided.

Notes:

盗人 can also be read as nusutto. The adjective may alternately be written using the kanji doubling mark, as 猛々しい, and/or with an old-fashioned conclusive form by leaving off the final い. Replacing takedakeshii with hanahadashii is an error.

Multiple sources translate this into English as “He bites the ear yet seems to cry for fear,” which I have never heard in my life. Some research indicates that in this case “bite” is slang for “caress,” as seen in Shakespeare’s Romeo and Juliet (Act II scene IV), but that doesn’t make the meaning any clearer or explain why someone thought it the best translation for what boils down to “brazen wrongdoing.”

Example sentence:

「ネコってさ、本質は盗人猛猛しいけど、家のペロちゃんは違うんだよ」

(“Neko tte sa, honshitsu wa nusubito takedakeshii kedo, uchi no Pero-chan wa chigau nda yo.”)

[“You know, by their very nature cats are bald-faced criminals, but our little Pero is different.”]