Most likely a lose wire\hard drive connection.
This is a good way for prank on your friend.
Check this up:
http://www.youtube.com/watch?v=qVhAf8I1Vck

Don't quote me on this, but I think I remember talk about RROD being a problem with a warped motherboard causing bad electrical contacts. Squeezing the console might bend the motherboard back to a better position, so it may be a temporary workaround.

IMO, the smart thing to do is to just send it for repair. A temporary workaround like squeezing the console will only make you risk having a later RROD after the warranty expires, at which point you'll regret having done it.

yeah it happens to me a lot during thunderstorm when I'm not behind a power regulator.... it their is a surge in the circuit it turns RRoD I just have to turn it off and on and it works... I'm still 100% RRoD less since feb 2006

The red lights cover a whole variety of conditions, not just RROD. People panic when they see them, but the vast majority of the time, it's that the system program didn't load properly, and a restart is all that's needed. Microsoft had seen a good number of consoles sent in that are actually fine. That's why they want you to call support and have them walk you through a few steps before they send you a coffin - to make sure you actually have a problem needing refurb.

It could have been a power issue.

We were at a friends house this weekend and had a power surge. Two of our consoles immediately showed the 3 red lights. Turning them off and back on solved the problem. The rings don't always mean a permanent failure.