Lick-and-stick postage stamps
Tell your grandkid that you had to lick a stamp before sticking it to an envelope and wait for her/his reaction. Youngsters might be pretty confused when they found out about it. If you used to lick and stick stamps, maybe you still have the taste of it as a reminiscence.
And you may wonder now if we can still find lickable stamps at certain stores. Short and concise: no… According to a U.S. Postal Service representative, since 2015, not a single water-activated postage stamp has been printed. Hey, but maybe you still have one or two inside an older cabinet. If that’s the case, show it to your grandchildren.