"Non-magic people (more commonly known as Muggles) were particularly afraid of magic in medieval times, but not very good at recognizing it. On the rare occasion that they did catch a real witch or wizard, burning had no effect whatsoever. The witch or wizard would perform a basic Flame Freezing Charm and then pretend to shriek with pain while enjoying a gentle, tickling sensation. Indeed, Wendelin the Weird enjoyed being burned so much that she allowed herself to be caught no less than forty-seven times in various disguises."
—Bathilda Bagshot, in A History of Magic
"Don't let the Muggles get you down!"
Ron: "HELLO? HELLO? CAN YOU HEAR ME? I - WANT - TO - TALK - TO - HARRY - POTTER -"
Vernon Dursley: "THERE IS NO HARRY POTTER HERE! I DON'T KNOW WHAT SCHOOL YOU'RE TALKING ABOUT! NEVER CONTACT ME AGAIN! DON'T YOU COME NEAR MY FAMILY!"
—Ron Weasley trying to use a fellytone
"THEN YOU SHOULD HAVE DIED! DIED RATHER THAN BETRAY YOUR FRIENDS, AS WE WOULD HAVE DONE FOR YOU!"
—Sirius Black, to Peter Pettigrew