The phrase "why not both" in Spanish can be translated mainly as "¿Por qué no los dos?" or "¿Por qué no ambos?" Both expressions convey the idea of choosing or having both options instead of one.

• "¿Por qué no los dos?" literally means "Why not the two?" and is a popular phrase, sometimes used humorously on the internet.
• "¿Por qué no ambos?" literally means "Why not both?" and is used in contexts where both options or choices are considered.

The choice between "los dos" and "ambos" can depend on the context and sometimes gender (masculine or feminine forms: "ambos" for masculine/mixed or "ambas" for feminine).