“Just Shoot Me” star David Spade was showing out-of-town pals the sights at Venice Beach when he spotted a guy selling knockoffs of his famed sister-in-law’s Kate Spade handbags. David dissed the dude, threatening to call the authorities! On his way home a while later, David passed the booth and . . . HELLO! . . . the Kate Spade knockoffs had gone buh-bye!!