"Pretend to throw an almighty punch, but instead poison your opponent!"
Secret Poison (シークレットポイズン) is a poisonous substance possessed by Frost in both of his arms.
In his right arm Frost contains a small, retractable needle coated with a non-lethal poison, which causes the opponent to become weak and disoriented momentarily by contact. In his left arm he contains a lethal amount of highly acidic poison with the intent to kill. While Frost claimed these poisonous needles were natural in his body, the Referee of the Universe 6 vs 7 Tournament stated there were clear modifications and enhancements.
In a panel of the manga, Frost is shown prepping his Secret Poison for the tournament, showing that it is not biological nature as Frost claims.
During his fight with Goku in the tournament, as it was clear Frost could not defeat the Super Saiyan, Frost decided to use his right arm to momentarily disorient Goku with a punch, also knocking him out of the ring, declaring Frost the winner. Frost did the same method to win his match against Piccolo, revealing his true colors. After this, Jaco pointed out Frost's retractable needles, and his body is inspected by the Referee, who disqualified Frost for using modified weapons. Vegeta offered to beat down Frost instead of him being disqualified, and Frost prepared to kill Vegeta with the poison of his left hand, ignoring the no-killing rules. Before he could do so, he is immediately beaten and knocked out of the ring by Super Saiyan Vegeta.
Video game appearances
In Xenoverse 2, it allows the user to disorient their opponent and inflict them with the poison status effect, then kicking them away. It can also be obtained by the Future Warrior (Xenoverse 2) by purchasing it from the TP Medal Shop (open from Friday to Sunday) for 50 TP Medals after the Version 1.05.00 Update.