Funny jokes-Optician

Waiting for my glasses to be repaired, I heard the optician trying to convince a customer she needed a stronger prescription.
“I’m fine with what I have,” she insisted.
“Okay,” he challenged, “what does it say on the store window across the street?”
“‘30% to 40% off all merchandise’ “
“That’s incredible.”
“Not really,” she said. “I never miss a sale.”