Many years ago, there was to be full eclipse of the Sun visible in Kansas. Two crazy friends of mine read that one of the ways to safely view it was thru a couple layers of exposed black & while film, so the went to the drug store to buy some.
   Having picked the cheapest one there, they headed to the checkout. As they approached, one said to the other, "Jim...are you sure this is what we want?"
   "I think so," replied Jim.
"Maybe we better double check," said Dwain.
   "Yeah, good idea!"
Whereupon, Jim opened the end of the box, popped the cap from the little container, pulled the film out and and unrolled it full length and held it up toward the ceiling while they studied it for a moment.
"Yeah, that looks right", Dwain said....and they rolled it up, put it back in the box, and paid for it and left, leaving the cashier and a couple bystanders just staring.