The phrase "I did" in Spanish is translated as "Lo hice." This comes from the verb "hacer" (to do), which is irregular and in the preterite tense for the first person singular (yo), it becomes "hice." When used in a phrase like "I did it," the object pronoun "lo" (it) is added before the verb, making "Lo hice" the standard way to say "I did it" in Spanish.