Well seems how we all want to get Flopper really bad, I wanted to start a discussion on ways we might be able to get it for people to try if they are looking for ideas. I invite you all to put your feedback and ideas on here as well. Here are the top three theories I have heard people mention and what I have come up with:
1. The Leaping-Nova zombies give you a free perk if you get through the round without getting hurt by them. This is pretty difficult but not impossible. As the rounds get higher it gets even harder but I think you are going to need to get all the perks available on the map through this free perk method. That's Juggernog, Speed Cola, Double Tap, Who's Who?, Quick Revive, and Mule Kick, which means you will need to get through two rounds of Nova Leaper zombies and get two free perks. Then on the third one you will need to get through it without getting hurt once more and I believe you will get Flopper. This would be the reward Treyarch would give you reward you for such a hard thing to do. This would be the reason that the perk machine is on the map but we can't get to it; it wouldn't make sense if we just got it without there being a perk machine, but Treyarch doesn't want to make getting it easy at all. It would obviously be the perfect thing to have on Die Rise. Remember the Mad Scientist round on Five, we could get max ammo from him, but if we killed him before he took anyone's guns we got Bonfire sale! In Ascension if the monkies never touched any of the perk machines we got a new perk. This is why I suggest taking no damage from those leapers because it could be a similar deal. This one has been confirmed to not work by many people but I am not quite abandoning hope that the nova leapers may have something to do with it.
Subclause A: It might turn out that all 4 players need to have all 6 perk before the game will give Flopper as the 7th perk. This should be tried as well before this is considered disproved.
Subclause B: On solo I have gotten about 5 bottles in a row including one without taking any damage from leapers, so I don't think that taking no damage has anything to do with it.
2. If the 3 rounds of the Leaper zombies doesn't work, then people have suggested using the Trample Steam on the elevator that drops and timing it just perfectly so that you get flung right into the room with Flopper. I almost guaruntee that WON'T work because you can't get into small landings and holes from jumping down from somewhere and, unfortunately, you will have a high velocity downwards as the elevator is nearing the door to jump through. Physics says we probably won't be able to get it that way.
3. The other thing I thought of, which is most likely not original is using a specific combination of keys in different keyholes, and possibly at the same time, or in a certain order. This would also make it extremely difficult to obtain flopper, which is why Treyarch would probably require that.
4. Another idea is that if you already have all 6 perks when you complete the easter egg, then possibly you may be able to get a 7th upon completion. The easter egg has been solved and only gives 6 perks, but I have yet to see any team who has 6 perks already go complete the easter egg. Until then this could be a possibility.
5. Another possibility I have been considering is that in the same way there are still areas on Tranzit that are mysterious and seem like they could be opened, this PHD Flopper might sit in that elevator shaft without being able to be obtained until the last DLC comes out and all the maps get an addon which opens them up further, or changes them in some way. I believe all 9 perks will be on Nuketown Zombies, I believe there will be something more in Tranzit, I believe Flopper will be opened, and that there will be many more surprises in all the new maps.
6. Is it possible that the key hole and red button down the hall from the bottom of the spawn elevator is an emergency stop?! What if while people were going down the person at the bottom put their key in and pushed the button? It would have to be timed just right but that could be a potential method for getting in the bottom or the top door to get at the perk... Anyone wanna try this to debunk it? I can't right now so I count on you.
7. This one is proven to kill you: Trying to get on top of the elevator either when it is coming up to you, or when it is going away will kill you. Go ahead and try it.
Feel free to also add anything you have tried that didn't work.