Fairy Trials is a Mental challenge introduced in Series 2.
The Caretaker's Explanation to the Game:
"For the little people, it's Judgement Day. To pass this challenge, the unfortunates must place the fairy traps into the exterminator, so they can get a real good look at them. If they decide it's a good fairy, they must release it. If they decide it's a bad fairy, they must blow it up. If they guess wrong three times, they will fail."