This OP was slightly more exciting to read before I noticed that this is a zombie thread.
Hello Waffle and welcome to the Straight Dope! I’m pretty sure that I’ve eaten candy that was older than you are now when I ate it. Still here to tell the tale.
True, it’s a zombie. But I’m still interested in what a very recent poster meant by:
It just seems odd. I don’t get it. What can you do with “untaken usernames”? Especially when there are more “untaken usernames” here than there are grains of sand on all the beaches of Earth combined.
Hey hey, learned colleagues, go a little easy on the 14-year-old newbie, yeah? No need to go maximum SDMB on them right from the get-go. 
Correct me if i’m wrong, but, at least in the case of the USA, aren’t expired labels just included for separate legal reasons and do not actually show when a food becomes unhealthy to eat? It is, after all, a “best by” date and not a “discard date.”
But if you combine all the grains of sand, there’s only one.
Pretty much. A lot of labels are actually “sell by” dates, not “eat by” dates.
My personal rule of thumb is that most refrigerated foods are good for 5-7 days after the date, as long as they’ve been kept properly cold. For candy and such-like, an item may go stale some time after the listed date, but it doesn’t really go bad.
Best-by dates are generally conservative, but there are caveats. One is that it very much depends on the temperature of the refrigerator – “refrigerated” is not scientifically meaningful. Being a bit skittish about such things, I keep my refrigerator just barely above freezing. I sometimes get ice crystals when I open a can of Coke. But OTOH, I can take out a package of sliced ham that I bought a week ago and it still smells as fresh and smoky as the day it was sliced.
The other caveat is that some things can be pushed well beyond their stated expiry dates but other things not so much. I’m fine with eggs that are as much as two weeks beyond their expiry date, but I’m much more careful about raw meats, and hypersensitive about raw fish.
There can be only one, sure, if you do that, but I don’t think immortal highlander sands have expiration dates. They’re “either or”
I don’t think we have heard from Tamex in a while. Too early to declare victory, Waffle.
We do have a ‘In Memoriam’ thread, so you have that going for you.
Actually, we haven’t heard from Waffle since his initial post, either. 
You are right about taking it easy on a new, young poster. I just found what they said a little suspicious.
I would interpret this as them saying that most places they sign up for, the name “Waffle” is already taken. I also was a bit surprised no one had signed up with that name before. Waffles are a bit of a meme online.
I’ve eaten eggs months after their expiry date. I use fresh eggs if I’m going to whip them, or eat them undercooked. But for muffins? If they look okay and smell okay, in they go.
Yes, i do break my eggs into a separate dish before adding them to the rest of the ingredients.
Raw meat and raw fish look, feel, and smell off when they get older. A you say, fish spoils especially fast, but it’s also especially obvious about having spoiled.
I go with the smell test. If you can get your nose close to something, it’s usually okay. If it’s bad, you can tell 12 inches away.
I always smell milk before I use it. I drank spoiled milk ONCE. Now I’m OCD about sniffing milk.
Raw chicken, when fresh, stinks. It’s even a little slimy. But there is absolutely no question when it is BAD.
When in doubt, throw it out.
~VOW
Altoids do lose their potency, starting when you take the plastic wrap off of the tin. I go through one or two mints a day, and I can definitely feel the difference when I start on a new tin. That said, even old Altoids are still refreshingly minty, just not burn-a-hole-through-your-mouth minty.
I’m not sure if the relevant factor is leakage through the seam of the tin, or the number of times the tin has been opened. If the latter, then a closed-but-not-sealed tin of Altoids might stay fresh and “curiously strong” for much longer.
When I buy the local chicken that was just slaughtered, it’s not slimy. But yeah, it gets slimy long before it’s bad to eat.
Expired Altoids and expired lip balm? 
Hard way to go, man. Hard way to go.
Sour milk is just immature cheese.
It is quite common where I live, (South Africa) and is sold in supermarkets in cartons just like fresh milk. I think the reason is lactose intolerance, which is fairly common here. I drink it because I like the taste.
I have to admit, if Waffle is only going to poster here once he made the perfect post.
Well done.
Warning: never, I mean never eat old Rolaids.
Not good. At. All.