For those confused by the joke here : In mahjong doras are bonus tiles, different each round, that if you have them in your hand when you score a hand, make your score go up. I guess here she means the Doraemon tiles (pun on "dora") which of course are not real mahjong tiles, so basically she just added fake tiles to her hand and counted them as bonus tiles.
Kinda like playing poker and saying she has four aces, and she reveals her hand and it's four Ace Attorney cards