Bye-Bye Ouchies!

Pain Pain Go Away is an execution in Danganronpa 2: Goodbye Despair, with Mikan Tsumiki being executed.

Sequence
Mikan lies on a bed. Monokuma, wearing nurse clothes, appears with a huge syringe in his hand. He runs toward the bed and prepares to inject the liquid in the same direction. Afterwards, the bed reveals itself to be an arm-shaped rocket that is surrounded by many buildings behind it, which Mikan sits on. As Monokuma injects the content of the syringe (maybe adrenaline or hormonal substance) into the rocket, Mikan starts to become more and more ecstatic before entering an orgasmic-like state. The rocket color changes from light brown to red, and then starts to launch. Monokuma hangs on the rocket with the giant syringe until the back of the rocket separates from the main body of the rocket. When the rocket launches into space, Mikan closes her eyes, and keeps holding to the rocket for dear life. She presumably dies from the lack of oxygen. After Mikan safely leaves the earth, Monokuma crashes to the ground below and becomes lodged face-first in the soil.

An alternate interpretation of Mikan's execution is speculated to be death by lethal injection.