I once worked with a fellow who was hard of hearing, and he said that the cause was trauma. For a while, I thought he was like Tommy, the pinball wizard who was struck deaf, dumb, and blind because he witnessed a terrible event. Then I realized that trauma can also refer to a damaging physical blow, or even a damagingly loud noise.
Take for example this well-known sentence:וכל המרבה לספר ביציאת מצרים, הרי זה משובח The Hagaddah at chabad.org translates it "and everyone who discusses the exodus from Egypt at length is praiseworthy." The הרי doesn't survive translation. And a case could be made that it’s a mere expletive in the sentence, nothing to worry about. But I think that it helps balance the short ending of the sentence against the long subject.
Troubles have always been with us, but it’s Rabbi Shmuel Hanagid — the eleventh-century scholar, poet, and Chief Vizier of Grenada — whom the dictionary credits with reporting he worked his way through an occurrence of tsara tsrura, “trouble in a bundle.”
The Targemni website gives “exciting, sensational” as its definition. Morfix, on the other hand, says “inflaming, inciteful.”
Shlomo Hillel (of all people), serving as Speaker of the Knesset in 1988, refers to the phrase as if it’s familiar. In the Knesset transcript, he says “I have the honor to call on MK Haim Ramon to present before us the proposal for insurance against vaccination mishaps. As I said, today every number’s a winner. Ein efes (There is no zero).”
Besides the question of whether one sincerely becomes a rhinoceros or just opportunistically fits in with them (although everyone in Ionesco's play seems sincerely won over), there is also the question of whether hitkarnefut means merely becoming like everyone else or becoming like a rhinoceros in more specific ways.