Q1: Is it grammatically wrong to say "¿Qué estás haciendo?" to a friend?
A1: No, it is grammatically correct. However, it sounds literal and heavy. Native speakers use it when they want to know what you are doing at that exact second, not as an easygoing greeting or a casual way to ask about future plans.
Q2: How do I reply when someone asks me "¿Qué haces?"?
A2: Keep it light. You can respond with Nada especial, ¿y tú? ("Nothing special, and you?"), Aquí descansando ("Just relaxing here"), or mention your activity directly with Cocinando algo ("Cooking something").
Q3: What is the most universal slang phrase for "What's up" in Spanish?
A3: ¿Qué tal? works universally across every Spanish-speaking country without feeling too formal or excessively regional. For casual peer-to-peer street slang, ¿Qué pasa? is widely understood everywhere, while ¿Qué onda? is ideal across Mexico and Central America.
