Buena onda

Buena onda is an informal way to say that someone is good or decent by nature. Él es buena onda. He's a good guy. It is frequently modified with bien: Ese chavo es bien buena onda. He's a great boy. Naturally, mala onda has the opposite meaning. Es mala onda. He's a jerk.

Here are some examples that refer more explicitly to behavior:

• Ándale. No seas mala onda. Es nada más por hoy. Don't turn me down (like a bad person would). It's just for today. Here, no seas malito/a would work as well.
• Pero no me peló y se portó mala onda conmigo. But he ignored me and treated me badly.
• Él fue mala onda contigo. He treated you badly, unfairly.
• No es por ser mala onda, pero .... I'm sorry to have to say this, but ...

Qué mala onda

Buena/mala onda isn't just for people. It can also be used for reacting to news or a situation.

• ¡Qué mala onda! That's terrible! (I'm commiserating here with the bad news you have just shared.)
• Qué mala onda, ¿no? That sucks. Sorry to hear it.
• Qué buena onda. Cool!
• Qué buena onda con lo de la boda. That's great news (about the wedding).
• Qué mala onda que se murió tu perro. What a bummer that your dog died. What bad luck.
• Pues qué mala onda que me ha echado la culpa. It sucks that she blames me. That's unfair.

As you can see from the final examples, qué buena/mala onda can be extended to specify the situation you are reacting to.

Se me hace mala onda

Se me hace buena/mala onda is a way to give your take on a course of action.

• Se me hace mala onda. It seems (to me) like a rude/thoughtless thing to do. A decent buena onda person would not behave that way.
• Vine con ella y se me hace mala onda dejarla. We came together and it would be uncool to abandon her now.
• A mí se me hace medio mala onda de tu parte que después de lo que pasó entre ustedes ... That's not very nice of you after everything the two of you have been through together.

En buena onda

A decent person, someone who is buena onda, does things en buena onda, with good intentions.

• Es es buena onda. It's for your own good. Not to hurt you.
• Lo he hecho en buena onda. I did it with the best of intentions.
• Creo que no lo hace en mala onda. He doesn't do it to be a jerk.
• Tú sabes que no lo hago en mala onda. You know I'm not doing it out of malice.
• No te lo digo en mala onda. I'm not saying this with an ulterior motive.

En buen/mal plan would work in these examples as well. Las cosas que hice, pues no las hago en mal plan.

Sometimes en buena onda can mean seriously.

• En buena onda. I mean it! (said angrily) I'm not goofing around.
• En buena onda, dame las llaves antes de que me encabrone. I'm serious. Give me the keys before I get pissed.
• Digo, en buena onda, ¿qué le viste en él? I mean, seriously, what did you see in him? (movie dialogue)