The great thing about Classics is that even the most boring of animals (which, let’s face it, sheep generally are) can turn out to be quite weird and wonderful after all. As a philologist, I’ve always been rather fond of Greek sheep, for two reasons:
One: they provide important evidence for pronunciation changes in the Greek language. If anyone ever asks you to prove that Ancient Greek was pronounced differently from Modern Greek, by far the easiest way to do it is to point out that Ancient Greek sheep go βῆ βῆ [bē bē]:
ὁ δ’ ἠλίθιος ὥσπερ πρόβατον βῆ βῆ λέγων βαδίζει
“The silly man goes around going baa baa like a sheep” (Cratinus, fragment 43)
Unless your interlocutor can find a breed of sheep that makes a noise like vee vee, you can at this point be regarded as having won the argument.
(The wonderfully onomatopoeic but sadly uncommon term βληχητά, “bleaters” [blēkhēta], will also do the trick.)