So, other than examples of other words that aren't acronyms, you have nothing to disprove what I said?
Technically, no, but given that it's common for people to make up phony acronymic origins for words, and that these always turn out to be wrong, the burden of proof should be on you.
I mean, think about it. Let's say what you say is true. Presumably, the practice we are calling "pimping" was already well-established as a part of medical education, but either students just called it "quizzing" or "questioning," or they didn't know what to call it. But then, somewhere, some bright medical student said to his classmate, "hey, that attending just really put me in my place. Hmm... put in my place. We could take the first letter of each of those words, and make a word out of it: pimp! Now we have something to call this practice!" Then word spread at that school, most people thought it was a good idea, those students talked to med students at other schools, they thought it was a good idea too, and the word caught on nationwide. Furthermore, this happened in a context totally divorced from any already existing word "pimp," meaning a man who organizes the services of prostitutes, since you say the etymologies are not related.
It sounds totally bogus, just like Gentlemen Only, Ladies Forbidden for golf, Port Out, Starboard Home for posh, For Unlawful Carnal Knowledge for f*ck, and all the rest. Much more likely that some medical student was daydreaming and thought to himself, "hey, wouldn't it be funny if pimp stood for something? Let's see, how about... put in my place! Yeah, that works!"
