dead chips, gambling chips that cannot be exchanged for money which must be used within the casino [written and colloquial]
Definitions (粵典–words.hk)
名詞
賭場入面唔可以換返錢，一定用嚟落注嘅 籌碼 gambling chips bought by gambling syndicates from casino management and offered at a discount to rich gamblers to use in gambling VIP rooms but which cannot be exchanged for cash; "dead chips"; literally, "mud chips"