I bought my son an operation at Toys R Us last year.  When we first played it, I thought he had a career as a surgeon.  He was able to clean out all of the bones and body parts without a single buzzer.  I remembered that when I was a kid, it was nearly impossible to get the parts out of the body without setting off the buzzer.  I was also a little annoyed that instead of realish body parts, the game was full of cell phones and head phones and other silly things.