Tiptup is a borderline Mario series character who first appeared in Diddy Kong Racing. He is a clumsy turtle who often gets stuck on his back - hence the name; 'Tiptup', a play on the phrase 'tipped-up'. He also appears as a recurring character in the Banjo-Kazooie franchise.
It is interesting to note that Tiptup physically appears different from Diddy Kong Racing in that, instead of being small and having a white shell with orange markings, he is a large turtle with an ordinary brown shell.
Tiptup may also have been set to make a reappearance in the cancelled game Donkey Kong Racing; as Taj the Genie, a character from Diddy Kong Racing was going to appear in it. It is unknown if Tiptup was going to appear in Diddy Kong Racing's cancelled Game Boy Advance sequel, Diddy Kong Pilot.
Tiptup returned as a playable character in Diddy Kong Racing DS. He sounds much younger in this game. As he's a Banjo-Kazooie character, it's odd how he reappeared in the sequel if Banjo, who became property of Microsoft when they bought Rare didn't appear.