Some of the decorative borders included with the Super Game Boy contain elaborate animations that normally appear only after the player leaves the controls untouched for a long time. According to a post from Supper Mario Broth dated November 1, 2026, a secret button sequence makes it possible to trigger those animations immediately.
The code is L, L, L, L, R. It can be used to summon Mario on demand, bring cats to life and reveal other hidden animations, the post states. The discovery shows that some Super Game Boy borders carried visual effects beyond their static designs, with the secret code offering a way to see them without waiting.
Sources: Nintenderos.