A trash medal is a term used in Round IV of the Liar Game Tournament. Trash medals are the medals with the names of players that are planned to lose. Trash medals become a very important item for Akiyama's strategy.
It is unknown who coined the term, but it's earliest mention chronologically is by Akiyama Shinichi while explaining his plan to Shima Takahiro to establish the Gaya Alliance. Trash medals are the medals of the players within Norhiko Yokoya and Harimoto Takashi's groups who plan on losing, allowing their designated winner to keep all their medals.
The purpose of trash medals is to buy votes from Gaya. The player lies and tells the Gaya that they are planning to win the game, and they give out the medals with their names on it. However, they are actually planning to lose and allow their respective winners of their groups to win and keep their medals. The only exception is Sakai Makoto, who believes that he will be the final winner of his group.
The Gaya eventually find out that the medals they have been receiving are trash, as they are told this by Shima Takahiro. It is later revealed that it is Akiyama that informed Shima about trash medals. The Gaya Alliance decide rig the elections so that it is a narrow margin to squeeze all the trash medals out of the two groups' possession. This proves to be unsuccessful as both groups just stop giving out medals altogether.
When the Gaya Alliance was first formed, Shima gathered all the trash medals and distributed it so that each member of the Alliance had one of each medal. He then gave all the remaining medals to Akiyama, who kept them to his group. This was all according to Akiyama's "winning" strategy. At the end of the game, Akiyama used medals belonging to Ikezawa Teppei to get everyone to work together. The idea behind this was for all members of the Gaya Alliance, Akiyama's group and Abe Yukiko to form a power play and stop Yokoya getting to his chair. By doing this, Ikezawa becomes the last player standing and his "trash medals" become winner's medals, which are worth 100 million yen each.
Players who gave out their medals as trash medals are the following:
*Ikezawa's medals ended up becoming the winner medals.
**Sakai believed that he would be the final winner and unknowingly gave out his medals as trash medals.