Prev5 of 10Next Use your ← → (arrow) keys to browse 6. National Sisters Day via Covealpa.com Sisters. You can’t live with them and you can’t live without them. On this day, let your sister know how much you love her, no matter how many times she steals your clothes. When: August 6th (first Sunday in August) Prev5 of 10Next Use your ← → (arrow) keys to browse One Response