I've done it before and found it surprisingly difficult but not impossible to break the egg. In order to break it, I had to put more pressure on the egg with my fingertips, which should probably be considered cheating.
I've seen this tested with an uncooked egg. A lot of pressure was required and when it finally broke the mess was unbelievable.
I went straight to the fridge and found I hurt my hand before I cracked the egg. I was as surprised as you are.
If that was a troll sir, it was a good one. I wonder how many HNers had to clean their kitchen today ;).