Captain Ginyu uses this technique after learning that Goku's power level is much higher than his own, with Goku's power being 180,000. Luckily for Ginyu, he has his Body Change technique, to swap bodies with someone stronger and more powerful. To make sure Goku does not interfere with his plans once he swaps bodies, Ginyu uses the Self-Harm technique in order to handicap his old body, punching a hole into the right side of his chest.
Appearance in video games
Self-Harm is depicted in a cutscene with Goku and Captain Ginyu in Dragon Ball Z: Budokai. The technique was named in the Budokai Tenkaichi video game series, where it decreases Captain Ginyu's health when used, but either puts him in MAX power or boosts his other stats. It also appears in Dragon Ball Z: Burst Limit.
Self-Harm appears in Dragon Ball Xenoverse under the name Holstein Shock. As in all other portrayals, it removes a good chunk out of the user's health, but has no secondary beneficial effects. It is also a custom skill for the Future Warrior (who can learn to use the Body Change technique from Ginyu). Its primary function in the game is the same as in the main series: to weaken the user's body in preparation for a Body Change. Its secondary use is activating Z-Souls that require the user to be in a critical state of health, lose a certain level of health, or receive a certain amount of damage.