Two recent linguistic observations:

1) When I recently bumped into the one (gay) (Colombian) graduate student who I know from the neighborhood, I started speaking (Spanish) with him, and he responded back to my asking how he was by saying something about how he much he has been working lately, but the way he said "trabajo" ("I'm working"), it's like the b was barely articulated or maybe even absent, and what was left was a lot like a long vowel in a word that sounds a lot like traajo.

When I pointed this out to him, he said that that happens with the way he says words like nada ("nothing"), too, like they sound like naa, and that that particular pronunciation practice confuses and annoys his (Brazilian) boyfriend to no end, when they speak (Spanish) together and he pronounces a word like that.

He also said that this is much broader than a (Colombian) thing, but when I told him that I don't hear pronunciation like that from my (Mexican) and (Guatemalan) coworkers, he said maybe it's because they take pity on me and speak slowly and enunciate whenever they're talking with me.

(Personally, I think it's probably that he's just not quite keyed into this linguistic feature and who uses it from where. It's very distinctive... I also pointed out to him that oblivion is the end result of intervocalic lenition of these sounds, like how Latin cadere "to fall" had already become Spanish caer, only now it's happening more and more everywhere.)

2)  A bit ago towards the end of one dinner shift at the one (Thai) restaurant where I work now, my one (smiley) (Guatemalan) coworker came up to me out of nowhere and started saying to me in (English) "Have a good night," repeating it over and over again and just smiling at me in between every time he said it.

And, he was just smiling, not only because it was like he was messing with me in a good-natured way, but also because he knew something in (English), though he then went on to ask me what exactly it meant, what he was saying.

Interestingly, his pronunciation was pretty amazing, and he even substituted out the final "-t" of "night" and put in a glottal stop instead, just like speakers do in casual (English).

You could tell that a native speaker had practiced that phrase with him, or that he had absorbed that phrase from overhearing native speakers.

You could also tell that his (native) language must almost certainly contain a phonemic glottal stop, for him to recognize and remember that sound there, in a phrase using the sound system of (English). It would be a very weird thing for him to pick up on and repeat, if he didn't already know that sound from somewhere.