I’ve been skipping over this thread because I thought, “Who hasn’t? What kind of question is the OP?” But hey, it’s a slow morning. I haven’t read the entire thread, but it occurred to me: Have I ever eaten a whole pizza in one sitting? I can’t remember!
As a kid, I certainly didn’t. What about as a teenager? Hmmm… my friends and I shared. Living alone? Pizza is perhaps a bachelour’s favourite food; I’ve certainly had a bunch of them. But it seems I eat about half, then have a couple of slices for breakfast and a couple more for lunch and/or for the next day’s breakfast. What about Tombstone frozen pizzas? They’re about “medium” size. Nope. Same pattern as I just mentioned.
Yes, I’ve eaten whole “personal size” or “small” pizzas. While I don’t remember a specific case, I’m pretty sure I’ve eaten a whole medium pizza in one sitting; but if I have, it’s been years since I’ve done so. “Large” or “manhole-size”? I’m thinking I haven’t.
Hm. The things this message board makes you think about…
i could, but only if i had a whole day to eat the pizza!
Stuffed crust with chicken and mushrooms, delicious!
Just a bit of advice for those who want to take part in competitive eating.
Stop, as often as you need to, to give a long BUUURRRRRRRPPPPP. I’m serious. Eating a lot, eating fast, and eating a lot fast, all generate gas. You have to let that gas out, or whatever it is that you’re consuming will sit uncomfortably on top of the gas bubble, and ultimately come back up, long before your stomach has taken in all that it can accomodate.
If you can’t get up a burp as soon as you feel it, massage your stomach, and when you feel it break loose, move to rubbing your esophagus in an upwards motion. Eventually it will come up, Barney Gumbel-style, and you will be able to continue.
I’m not kidding. I once won a pizza-eating contest this way, against guys who were larger and more notoriously rapacious than I…but they didn’t know about this. (FWIW, I was told the secret by my Italian relatives. We weren’t having a contest; they just noticed that I hated saying “I can’t…” to dessert.) It wasn’t ladylike, but it did win me a free special.
Also, Mr. Rilch once lost a similar contest in high school, which he otherwise could have won, if the other contestants hadn’t gotten away with going outside and punching each other in the stomach between rounds. If you’re ever in such an eat-off, you must insist that all contestants should be monitored until the final decision.
Yup done it many times actually. Large Domino’s pizza? No sweat. There is a nice little pizza place from my hometown that makes awesome pizza that is a bit bigger than Domino’s and I can still stuff it down without a problem. Now if anyone knows of Luca pizza (fairly popular in Indiana or so it seems) if you can eat one of their pizzas whole well then damn your good. It’s not all that much bigger than Dominos but sheeet man it is absolutely covered in toppings and whatnot.
Hell, man, I did it yesterday. I also use a 2-liter jug for a cup. 
You people ought to see my grocery bills.
Heck yeah. I ate a whole Papa John’s 14" (double cheese, tomato, black olive) on Saturday. This was about 8m, and
I hadn’t eaten anything since breakfast.
-Ben
Back in the day, when I could eat 15 pounds of anything and lose weight at the same time, I ate not one, not two, but three large Pizza Hut pan pizzas in the same day. Two in the restaurant, and one at home a short time later. I was hungry. 
Now I eat one slice and gain 20 pounds. sigh Where did my youth go? Apparently into my stomach. 
Once . . . a long, long time ago.