It's not a cosa. It's "not a thing". Direct Spanish translation: a "nothing thing". A cosa nada refers to something that is not a problem, not anything worth sweating, not worth anyone's time. Used to minimize something that doesn't deserve or need any attention or emotion.
Boyfriend - "So your "friend" Nick, did you guys ever date?"
Girlfriend - "Omg no, we kissed once in 8th grade but it was a cosa nada."
Girlfriend - "Omg no, we kissed once in 8th grade but it was a cosa nada."
by FreebirdG2M June 10, 2019