¿qué onda? / kay OWN-da? / what’s up?
If you’d like to be something of a social butterfly and interact with other people in Mexico, phrases like qué onda become a good way to informally greet others, along with other ones you probably know like qué paso or qué tal. Be sure to use it with a friendly tone of voice, since qué onda can go from “what’s up” to “what’s your problem” based on body language and inflection — we don’t want any big Samoan dudes bodyslamming anyone based on miscommunication, now, do we?