In Part 2 of our chat with Arturo Vega, artistic director of The Ramones, the interviewer asks:
¿Entonces tú estudiastes [sic] esto? ¿Estudiastes este arte o eso ya fue algo que tú...?
Then did you study this? Did you study this art or was it something that you...?
Captions 45-47, Arturo Vega - Entrevista - Part 2Play Caption
If you've studied basic Spanish grammar, you've probably learned that the correct second-person preterite of estudiar (a regular, -ar verb) is (tú) estudiaste without a final 's.' So what was the interviewer saying -- not once but twice? Was she so tongue-tied in the presence of Vega that she couldn't speak her own language without adding stray s's? Or was it simply a manner of speaking that you don't come across in textbooks?
Elsewhere in the interview, we heard the same -astes ending on another -ar verb:
Que otros artistas que... quizás nos están viendo hoy pueden a... aprender algo más de cómo tú desarrollastes tu... tu... tu trabajo.
That other artists who... may be watching us today can be... can learn something more about how you developed your... your... your work.
Captions 6-8, Arturo Vega - Entrevista - Part 2Play Caption
(Use the "slow" button on the Yabla player and you'll hear that there's no mistaking that there is a final 's' there.)
After asking around (and browsing online), we found that some Spanish speakers in many countries (Spain included) do indeed say (tú) estudiastes, even though it's considered improper. People also say things like "(tú) comistes" and "(tú) dijistes," equally frowned upon by grammarians.
Among professional translators and other highly educated multi-lingual folks, we found heated debates on message boards about -astes/ -istes. Some say the endings came from the Spanish vosotros (-asteis/ -isteis) form. Some note that all other endings for "tú" verbs end with an "s," so it comes as a natural extension of Spanish grammatical rules ("pattern pressure"). Some argue it is acceptably "casual" in some settings while others insist it is dead wrong and painful to hear.
As you yourself navigate la habla hispana (the Spanish-speaking world), there is a good chance you will continue to encounter this usage. You may have even already danced salsa to such tunes as Cuando Llegastes Tú (Louie Ramirez) or Llegastes Tú (Ray Sepúlveda). Unless your spoken Spanish is of such an extremely high level that you can easily slip in and out of "dialect" depending on what community you are socializing in (and you really feel compelled to "fit in"), you probably don't want to adopt this style yourself. And when writing, it's definitely best to refrain altogether.