Hoops work as targets in clumsy ninja. Essentially they are basketball hoops which you can throw your ninja through or get him to go through willingly. You earn XP every time he travels through the hoop, while each interaction also reduces the 'health' of the hoop. Use it a certain number of times and it will break - at which point you will have to purchase a new one.
Below you can find a list of all the hoops available in clumsy ninja:
Cost: 90 Coins
Earns: 60 XP
Unlocked: Level 5
Cost: 100 Coins or 22 Gems
Earns: 410 XP
Unlocked: Level 8
Cost: 4,200 Coins or 30 Gems
Earns: 3,500 XP
Unlocked: Level 20
Cost: 20,000 Coins or 36 Gems
Earns: 6,000 XP
Unlocked: Level 8
Cost: 24,000 Coins or 244 Gems
Earns: 11,000 XP
Unlocked: Level 32
Cost: 59,000 Coins or 60 Gems
Earns: 16,000 XP
Unlocked: Level 39