This happened in a store once. I was there with my then 2 year old. We were next to a rack of bikes when BANG!!!! A random tube on one of the bikes gave out.
My 2 year old looked up at me, saw I wasn't scared, and just smiled and ignored it.
The store manager gave me a 10% off coupon because it DIDN'T scare the kid and make him cry.
Ironically...I was there to buy a spare inner tube that day. The same spare inner tube I will be putting on my bike in about an hour.