I have a likely theory. Remember ZZ Top often has a Mexican theme, so the answer is in Spanish. Most likely the song is a takeoff of a gospel song which would originally said something like “have you heard about Jesus” or “have you heard about my lord” or some such. I’m guessing they softened it and used a Spanish phrase. In Mexican accent, “yo” is often pronounced “cho” which someone thought was “jo”. My theory is that they’re saying “have you heard about yo te ama” which is a way of saying “I love you”. That seems to make the most sense.
I have a likely theory. Remember ZZ Top often has a Mexican theme, so the answer is in Spanish. Most likely the song is a takeoff of a gospel song which would originally said something like “have you heard about Jesus” or “have you heard about my lord” or some such. I’m guessing they softened it and used a Spanish phrase. In Mexican accent, “yo” is often pronounced “cho” which someone thought was “jo”. My theory is that they’re saying “have you heard about yo te ama” which is a way of saying “I love you”. That seems to make the most sense.