This phrase is not a slang term but a literal one, meaning 'another twenty pesos'. However, in some colloquial contexts, it can be used metaphorically to refer to something additional or unexpected that one has to deal with or pay for.
Examples
- Spanish: Después de pagar la multa, el inspector me dijo que debía otros veinte pesos por una tasa administrativa.
- English: After paying the fine, the inspector told me I owed another twenty pesos for an administrative fee.