Vos
"Vos" is a second person singular pronoun used by many speakers in certain "familiar" relationships or informal contexts. Voseo is most commonly used in the university context between students. It is also widely use between friends, family, people of the same age etc. Some adults use "vos" in order to address children or juveniles, but other adults address everyone regardless of age or status with "usted." Costa Ricans tend to use 'usted' with foreign people.
Read more about this topic: Costa Rican Spanish, Second Person Singular Pronouns