National Slap Your Sibling Day Share definition Flag A national holiday where you can slap your siblings! It’s a wonderful day. “Hey, sister.” “Hey, what’s up” “Happy national slap your sibling day!” “Wha-“ *slaps* National Slap Your Sibling Day by yourveryownmother October 28, 2020 0 0 Get merch Get the National Slap Your Sibling Day mug. Buy Now — $32.95 See more merch