How does that happen???

As best I have been able to gather, it's based on an hourly formula, but also an on a curve across a multi hour span. Consistant memes tend to sit in one spot while another may have a vote/comment/view spurt over a couple hours that pushes another past the slow and steady meme. This usually tends to happen after a meme has peaked in its views/votes/comments per hour. So in short its momentum based as best I can tell.

Thanks! That confused me so much. I guess thats why the front page doesn't rearrange every time you refresh

Right, the front page refreshes hourly. I know that's not the clearest explanation, but if you can hit the front page a couple of times, you can actually develop a feel for if one will make it or not. I'm hoping to get 6-8 upvotes when my memes drop with a couple comments. Its key to respond as it creates curiosity. 6-8 with 8-10 comments in the first 12 hours should make page 10 on the hot stream. From there you'll get an honest amount of views to see if it will go all the way or not.

John is right

And is it REALLY John??

It really is!

I WON'T LISTEN TO YOU MARK ZUCKERBERG!!! GO BACK TO SATURN!!