Okay. I take a full attack action. Assume that I have, from various sources, a total of five attacks as part of a full attack sequence. I roll to attack, and I succeed! I do, let's say, 2d6 damage (I know, but it makes the example easier), but the Ogre in front of me is still standing, the cad and bounder!

I roll again. I hit! Because I have hit once before, I get to add one to my damage. So that's 2d6+1. But this guy's still standing. Just not an ounce of quit in him, I guess. Not to matter, I have more attacks left for him!

My third attack, I roll a natural twenty, and then confirm the critical! Huzzah and amazement! So my damage is 2d6+2 (because I've hit him twice before this round,) times the critical multiplier of let's say three, making a total of 6d6+6.

If that doesn't drop him, I'll just keep going, but on my fourth hit I roll a natural one. Obviously here, I do no damage.

I have one attack left, and I hit again. However, since I missed, that resets my number of consecutive hits, and I'm down to just my normal 2d6. Hope it's enough!