Rocket uppercut is a movement technique that propels Jak vertically while maintaining a grounded state. The technique has applications in many speedrun categories and is one of the key components in Lava Tube Skip. A rocket uppercut is performed by uppercutting into a small piece of vertically oriented ground collision. During the uppercut, Jak makes brief contact with the vertically oriented ground collision which sets him to a grounded state. This brief contact also amplifies the vertical momentum from the uppercut, similar to the amplified horizontal momentum of a boosted uppercut. The end result is Jak flying up into the air in a grounded state able to perform a limited amount of movement options before descending and entering his falling state.