The "What If?" game!

Then Mowing the lawn just got that much more badass.

What if every time you think something up, you create a dimension?

According to the Nerd's Theory of Diverging Realities, you do!

What if WE'RE the Time Lords, and we simply haven't developed sufficiently? What if everyone else who hasn't come into being is counting on US to provide a Doctor?

If we're the ancestors to what will become the Time Lords, that would actually make the Doctor's adventures more "self-preservation" rather than "saving these flawed but fascinating sapients because I'm just that kind of guy".

What if people could jump as high as Mario (several times their own body height)?

Then we would need much higher nets of basket ball

what if there was no illness?

I can't say about specifics without details; but, every "illness free world" plan I've seen had side effects that resulted in a "Call the Doctor" end of the world scenario.

What if the monkey-god said "Let there be ninjas!"

That would explain the decidedly-not-stealthy ninjas of Naruto, given that monkeys aren't known for their stealth.

What if the world had actually ended on the 21st?

Then this is either heaven, or hell; I'm not sure I want to know which.

What if, in turn, the snake-god said, "Let there be pirates!"

Then there would be a war to end all wars! (Ninjas win)

What if the answer below is false?

404: DO NOT MESS WITH TIME

What if we found some way to link our world with Equestria?

Lauren Faust goes "FFFFUUUUUUU-!"

What if you could only use the word "muffin"?

muffin muffin-muffin mufmuffin

What if evolution worked in real life like it did in pokemon?

What? Tyger is evolving!

Dun dun dun dun dun duuuuuuu dun dun dun dun dun daaaaaaa dun dun dun ding!

Congratulations! Your Tyger evolved into Tyger Burning!

What if everyone started spinning around simultaneously?

The Earth would stop spinning, fly off its orbit, crash into Jupiter, and explode, extinguishing all known life in the universe. In other words, probably not the best idea.

What if seeing was believing?

Then musicians would have it a lot tougher.

What if the earth's mass (but not dimensions) suddenly doubled?

Then the earth's energy would be doubled.

what if sasquatches were once the dominant species?

"The Age of Hair is ending; we must now retreat to the woods. The Age of the Short Baldies will soon be upon us."

What if the next "big invention" rendered your chosen profession obsolete (Modern computers: Punch card operators, Supermarkets: Milkmen, etc.)?

For me? Goat milk won't become truly obsolete, because they'll never be able to synthesize it perfectly enough. If they came close, then the real thing would skyrocket in demand, and I'd be able to name just about any price I cared to for the stuff.

What if every time someone rolled a 1D100, a Tons Of Fun effect occurred for real nearby?

Not much would change, since most people only roll 2d10 instead of 1d100. I would, however, be able to cause madness to breakout wherever I wanted.

What if you really couldn't believe it wasn't butter?

I should not be putting this butter on my bread...

What if magic the gathering was an anime?

It'd either be really awesome or perceived as a Yu-Gi-Oh clone.

What if they kicked Ash out of the Pokemon anime?

Then we would finally get both of a region's player characters.

What if the Joker laughes at you?

Run. Run like the Devil himself is after you, because he is.

What if all the versions of the Joker met each other?

Then we would need every single version of Batman to stop him

What if people got the beatles references in this topic?

Then we'd get by with a little help from our friends...

What if everyone had a secret except me and my monkey?

Then the undercover cop who had a sister named Jan would find out the secret of the monkey man

What if there was no heaven and no hell bellow us?