thank you

A Mum decided she was no longer going to remind her teens to write thank-you notes. That year their Aunt never received thanks for the checks she gave the teens for their birthdays. The next year things were different. The teens each visited to thank her in person!
“What caused the change in behaviour?” a friend asked the Aunt.
“Oh, that’s easy.” the Aunt replied. “This year I didn’t sign the checks.” 🙂