The Lucky 7 is a special item that made an appearance in Mario Kart 7, which gives the user seven different items: a Banana Peel, a Green Shell, a Red Shell, a Dash Mushroom, a Super Star, a Bob-omb and a Blooper. It is depicted as a red number "7", matching the one from the game's logo. The name originates from a symbol on slot machines, where three sevens results in a jackpot.
Dry Bones Kart series
The item makes its debut in Dry Bones Kart 7, where it functions exactly the same as in Mario Kart 7.
It returns in Dry Bones Kart 8 and will return in its port. Dry Bones Kart 8 introduced the Crazy 8 in that game as well, functioning identically to a Lucky Seven, except it gives the player eight items instead of seven (with the eighth item being a Fake Item Box).
The Lucky 7 and Crazy 8 are both going to return in Dry Bones Kart 9. Dry Bones Kart 9 is going to introduce the Cloud 9, functioning similarly to the two aforementioned items, but will give nine items (the ninth item is going to be a throwable Thunder Cloud, hence the name).
The Lucky 7, Crazy 8, and Cloud 9 are all going to return in Dry Bones Kart 10. Dry Bones Kart 10 is going to introduce the Perfect 10, functioning similarly to the three aforementioned items, but will give ten items (the tenth item is going to be a POW Block).