can't make heads nor tails of (someone or something)

can't make heads nor tails of (someone or something)

To fail or be unable to understand, decipher, or make sense (of something) in the slightest. We tried identifying the hieroglyphs on the ancient tablet, but they were so archaic that we couldn't make heads or tails of it. See if you can figure out what this contract is saying—I can't make heads or tails out of all that legal mumbo jumbo.

See also: head, make, nor, of, tail