Lucky Egg

A Lucky Egg is an item in Pokémon Go. It can currently only be acquired by purchasing one from the Shop for, or by leveling up.

Details
The lucky egg does not hatch into a Pokémon like a normal egg, but instead doubles XP gained for 30 minutes. This effect lasts whether the player is online or offline, so it is important to only open one when you have enough time to capitalize on the gains.

In-game description
''A Lucky Egg that's filled with happiness! Earns double XP for 30 minutes.''

Trivia

 * A Trainer receives one at levels 9, 10, 15, 20 (×2), 25, 30 (×3), 35, and 40 (×4).