My friend thinks that if you put a massive straw in the ocean, which went all the way out of the atmosphre into space, the vacuum in space would sck up all the ocean...

I don't think it will happen, but it's a good point he made

At some point in the 22,000 miles long straw, gravity will overcome the suction. It's still a worthwhile goal, as putting a monorail outside the straw will get us into orbit.

Interesting.
I have no idea, but just want to add to Cats comments:

Space elevator - Wikipedia, the free encyclopedia ;)

I think I must be missing something - the straw would have the same atmospheric distribution as the planet does... having a small cylinder of plastic doesn't change anything

Ben221: Your friend is wrong. The longest straw that you could ever build to suck up water is about 32 feet high. That's because atmospheric pressure - which pushes down on the ocean surface and causes the water to moive up the straw when you put a vacuum on the upper end - is equal to the pressure at the bottom of a column of water 32 feet high. If you have a straw that is longer than 32 feet, and put an absolute vacuum at the top end, the water column will rise to 32 feet and then stop there - it can never go higher. So to answer the question - if you could build a straw that's 100 miles long so it reaches into space, the water would climb to about 32 feet and then not go any higher. The oceans are safe!

As a practical consequence of this - if you need to pump water up hill more than 32 feet high, the only way to do it is with a pump at the bottom of the hill that pushes the water up hill, as opposed to a pump at the top of the hill that tries to suck the water upward. That's why the pump for a water well is always placed at the bottom of the well, not the top.