What preposition is used with "sit" and "computer"?

I personally would say "to sit at the computer", but a friend of mine said he heard "to sit on the computer" from a native speaker. That does not sound right to me at all, and I trust my guts, but still, Google results for "sit on the computer" are quite numerous (even more numerous than "sit at the computer"), and I wonder if on sounds right to native speakers out there.

Thanks for your input!

Solution 1:

One can be "on a computer", which means one is using it. In order to do that, one sits at it.

To sit on a computer does actually imply sitting on it.

OED:

on, prep.
3. Indicating the instrument or medium of an action or process.

Solution 2:

I've got many British friends, and they frequently use this construction. That's not to say that it's exclusively British, but I cannot recall having ever heard it before then; however, if you parallel "to be on the computer" to "to be on Skype" or "to be on Facebook," it makes perfect sense.

I have actually caught myself using it a few times. In my opinion, it's all relative in the computer world.