know which end is up

== English == === Etymology === From the common marking this end up on parcels to guide proper transport. === Pronunciation === === Verb === know which end is up (third-person singular simple present knows which end is up, present participle knowing which end is up, simple past knew which end is up, past participle known which end is up) (idiomatic) To possess sound judgment or common sense; to have a clear understanding of a situation. Synonym: know which way is up ==== Usage notes ==== Frequently used in negative constructions to discuss inexperience or failing to understand a situation. Cf. know one's ass from a hole in the ground. ==== Translations ==== === See also === know one's way around know which side one's bread is buttered on