The trend of using the last part of words, bot for robot or za for pizza for instance, appears to be from the late ‘60s as suggested by Etymonline:
The method of minting new slang by clipping the heads off words does not seem to be old or widespread in English. Examples (za from pizza, zels from pretzels, rents from parents) are American English student or teen slang and seem to date back no further than late 1960s.
Another term that is now widely used in social media networks is rents (parents).
Did this counterintuitive usage of the last part of words originate simply from students jokes or are there previous literary usages that may have inspired those students in the late ‘60s?