So in all the excitement, we may have forgotten to tell you just exactly how to do turtle tipping in Super Mario Bros. because the NES version is actually different than the Super Mario All Stars remake. In fact, the All Stars version is easier to do.
It may not be obvious from the footage, but Mario can't jump on the koopa shell indenfinitely in the 8-bit version. In fact, even if you're doing it right, it's hard to start. Even though in the All Stars version you see us doing the trick by jumping forward toward the shell, it's actually a lot easier if you don't do that. In fact, there are some hit detection problems, which is the reason it works at all. One might say, between capping the life counter, and adjusting some of the hit windows, Nintendo actually deliberately made it easier in the 16-bit version!
But enough about that. Let's dive into the classic.
First, everything we said about approaching the shell is still true. You want to jump on it so the shell is hanging at least a bit over the edge of the step -- otherwise you're never going to get it to start off properly.
Then, you need to position Mario on the step below. And, this is the tricky part -- get as close as you can to the shell without touching it. You can get up against it with no pixels to spare, so don't be too shy. But you gotta do this before the koopa starts stirring and walking around again.
Oh, but this isn't going to start it. This part is to just get you close enough. At this point, you might get one or two good hops, but Mario is going to just fall through, with the shell (which should have bounced at least once) hanging out behind his head. You can do this forwards or backwards -- Mario's head doesn't care! (Incidentially, this poor head hitbox detection is also why the Minus World trick works.)
Now you can get flush with the front of the step where the koopa shell is hanging out. Now all you need to do is jump and keep jumping.
More or less. It might take a few tries to get the richocet going. You have to jump at the right height, otherwise again you will only get a couple of good taps in -- not enough to get to a single 1-up, let alone many. Face forward or backward, whatever seems to work better. You'll know when you hit the sweet spot, because you'll get about a dozen extra lives.
Unfortunately, that's the best you can hope for in one run. You have to actively get Mario to start jumping and do the cycle all over again. The good news is that the more time you have on the clock, the more often you can do this. Or, if you're good with risking glitching out the game, you can time out and try all over again with the wealth of lives you've earned. Of course, the glitch in this case isn't some kind of Minus World-like code error; there's just a point where you will get a "GAME OVER" screen instead of being able to continue, so make sure you keep track and don't go over 127!
Even though it requires being more active than the 16-bit version, you can still rack up a lot of extra men.
(That seems mildly inappropriate.)