As a DM, I’m used to players trying to find loopholes in rules but only once happened to me of a player who actually took the rules and enforced them to the extreme.
Long story short, the party I was DMing for, in Pathfinder, was fighting through cultists of an ancient god, racing against time to prevent a ritual that, if completed, whould have opened the doors of reality to all the god’s minions. While they were cleaning up another room, they found a Pit Fiend, chained to the floor and bound by magic. Curious, the talk to him and he explains that the cultists had captured him with powerfull magic and were planning to sacrifice him to power the ritual. He then makes an offer to the group: if they free him, he will grant them a free wish.
Now, the group knows how much I like to twist Wish, expecially when the caster is an evil outsider, known to turn badly formulated desires into a recipe for regret. So I say to the group that the session ends there and they have the week to think about the offer. We are all about to leave when this players asks me a question:
“Last time I bought 50 gp of paper, how much is it?”
Not wanting to go find the exact gold-to-paper ratio, I answer him that paper is not exactly cheap, so he’ll have something like 25 sheets of paper with him.
“Not much, but I think it will suffice” he answers.
By that I should have knew something bad was going to happen.

Next session cames, and we start from where we left. Everybody is proposing their ideas, but no one passes for the party finds everytime a loophole or something that could be used against us.
It’s paper-player turn, and I ask him what his proposal is. He just smiles to me and then takes out from his pack a stack of 25 paper sheets, each and every completly written in fine print. Seeing my confusion he just says:
“It’s for the wish. A contract. Isn’t that how devils work?”
He had actually written twenty five damned pages in strict burocratic language, complete with subparagraphs and notes.
Now, Wish says that, for particular complicated wishes, you can simply negate the wish, but I wanted to award his interpretation and solving the problem while staying in character (he had very high ranks in both Linguistic and Knoweledge (planes)), so I said that the wish had been granted and he got a map of the cultist’s base.

Yes, he had written a 25-pages contract to request a map.