Cats & cucumbers, Friend or foe?

Lately I've been getting many posts showing videos of cats being startled by the ever so friendly and innocuous cucumber. Apparently many cat owner are sneaking up behind their cats and depositing large cucumbers unknowingly behind their cat's back. The sadist cat owner waits in hopes for their cat to notice and jump suddenly with superhero rise into the air on all fours. It's quite a sight and I must admit the videos I've seen are hilarious. 

With guilt, curiosity and laughter I can't help but wonder.....Why do cats react this way?  

Some say cats have genetic predisposition to be scared of snakes and the cucumber has activated their instincts to protect itself. Have we activated their dormant snake-avoidance reflex?

Is this good or bad for my cat? I feel two ways...I suppose it is good if it teaches Lucky to avoid those rattlers perusing the yard if you live in the Arizona desert.  As for the most of us it may cause more stress on your pet and it is probably not a good thing.