Will I be able to use a Canon EF 70-200mm f/2.8L IS USM II Lens on a Nikon d5000?

Friend has a canon camera and I used her lens on my nikon and it worked but this one is bigger.

Your friend's Canon lens worked with your Nikon dSLR? How? Why?

The mounts are totally different. The lens indexes are miles apart (not literally though). The only way it would work is if you used an adapter!

It does not matter if the lens is big or small. What's important is the mount. The Canon EF-mount is different from the Nikon F-mount. That's how it is and that's how those two brands divided our world as most people know it.

How did you use the Canon lens on Nikon or vice-versa without any adapter? But I don't think you'll find one that uses EF / EFS for Nikon D5000.

The bigger lens will mount the same as whatever Canon lens you used before, so you can use it just like the Canon lens you used before. Since the mounts are incompatible, maybe you held the lens against the body?

It is not possible to adapt a Canon EOS lens to a Nikon F body. The Canon flange is wider.

Absolutely not, get a Nikkor 70-200 2.8 VR2