Definition of the word piss off

The expression "piss off" is a rude and colloquial way of telling someone to leave or go away. Its origins are unclear, but the phrase seems to have emerged in the mid-20th century in British English slang. The word "piss" in this context is not referring to urine, but is an anglicized version of the Irish expression "pish tos," which was adopted by the British army during the Second World War. "Pish tos" is an Anglo-Irish phrase meaning "nonsense," and is thought to derive from the Irish Gaelic "braith meaning" (breathonn cumhatha), which refers to the scattered seeds of a plant that cannot grow unless they are pressed together. The phrase "pish tos" was in common use in the military, and similar phrases such as "pish and tos," "pish toshers," and "piss and tosh" gradually became more widespread in the general populace. "Piss and tosh," which was used to dismiss something as unimportant or foolish, eventually evolved into "piss off" as a way to dismiss a person. The exact reason for the transformation from "piss and tosh" to "piss off" is uncertain, but some theories suggest that it may have been shorthand for "piss and tosh, and don't come back," denoting a definitive and final rejection of the person in question. While "piss off" is still considered impolite and vulgar in some contexts, it has become a commonly used expression in British and Australian English, particularly among younger generations.