I'm a dyslexic ADHD bum...

Part 1

I think that because he spent time in various foster care facilities and lived in an area with a large number of Spanish speakers, he was either taught or forced to learn it (thinking about him as if he was born and lived in Texas).

He may even have been placed with foster families who were Latino or Spanish-speaking, and he probably got used to hearing the Mexican accent and become able to understand it, maybe not the best speaking it, but still, he could defend himself talking just what he need to say.

I also like the idea that he learn Japanese with Shiro at home and since his father was Japanese, he wanted to keep as much from his father as possible.

So here it is, our trilingual boy, stuck in space piloting lions and some day Lance is missing his home and he WANTS to speak Spanish so bad so Keith tell him that he can understand Spanish and Lance starts talking like his life depend on it only for Keith to find out that he can´t fucking understand a word. Hes talking to fast and because the accent hes not sure if the words are what he think they are and maybe when he thinks he understand the context of what Lance is saying he starts using Cuban slang that he doesn't fucking have idea what it meant.

So when Lance finally stop his monologue and look at Keith just found the dumbest stare he has ever seen on him, and IMMEDIATELY bursts out laughing.