Can’t make heads or tails
Have you ever seen people flip a coin in the air to choose between two alternative? Depending on which side is showing when it lands — head or tail — a final decision will be made with two options.
“Can’t make heads or tails” is an interesting idiom that is related to this random decision-making process! This idiom means that you are unable to understand something (or someone) mainly because it is puzzling or unclear. It is believed that this idiomatic phrase dates back to Ancient Rome. According to a number of websites, Cicero used the expression, “neither head nor feet (ne caput nec pedes),” which refers to a state of confusion.
While British often use a singular form (can’t make head or tail), in American English culture, the plural form is more commonly used by the speakers. A current example would be: I spent several days working with this new programming language but, unfortunately, I still could not make heads or tails of it.