Wine, Great Attempt or Poison?!
I think your 'home brewer' as other 'answerer' is correct. Most anything CAN be fermented and turned to some sort of wine or alcoholic beverage, BUT in very sterile and 'sound' ways! Its not worth taking a chance on it...too much CHANCE of making someone sick OR WORSE. LOTS of people do the home 'brew' think in making wine and ETC...! But 'you must know what you are doing.' Don't take the chance...pour it OUT. In the day we are living in IF you served it and someone got sick or (worst case scenario) DIED...you could likely be charged with a horrible crime!
It probably wont poison you, it probably will taste horrible. There is a slight chance I'm wrong about either of those, if its really fermented and created alcohol its not going to hurt you but the odds it tastes good are low.
You can intentionally do what you have described to make wine(add yeast to juice), but with wild yeast and the high chance that (not harmful but produce off flavors) bacteria have infested it and turned it into something that taste bad are reasonably high. When you do this intentionally you use known yeast strains and work with sterile containers/etc
I'm a homebrewer and I make beer and wine
* Colleen Doran uses this early on in her comic A Distant Soil. Jason is offered some wine by the seemingly-kind Sere. He asks her to drink hers first, which she does. He then takes a few sips of his. One of Sere's servants then enters with a small metal tube, which Sere injects into her arm—it's the antidote. (Or inhibitor, or something—it's just drugged, not poisoned.) Cue Jason falling over.
* In a flashback in Batman R.I.P, we see Bruce Wayne drinking with a little Asian man in the Far East. The man then reveals he poisoned Bruce's cup. However, the man himself begins to fall victim to the poison. Turns out, according to Bruce, "You blinked. I switched the cups. Force of habit."
* The very first Spy Vs Spy cartoon in Mad Magazine featured the black spy and white spy both subtly disposing of the tea they were supposed to be having by tipping it onto the floor. Two cats see the tea and lap it up, and are shown dead in the final panel.
* Played With in a Nikolai Dante story in a scene between the title character and his half-sister Anastasia, who typically kills people by poisoning them. When having a drink together, Nikolai's crest warns him that his glass may be poisoned, so he makes an obvious effort to switch the glasses, at which point Anastasia remarks that, as an experienced poisoner, she would expect a wary individual to try and switch glasses, so she would logically poison her own glass, instead. Then, when Dante switches glasses again, she remarks that since she's immune to her own poison, anyway, she would logically poison both glasses.