There's an awkward thing that happens when you're immersed in a foreign language...
Here's the situation, it's break time at work, everyone is gathered round the coffee pot/water cooler/tea station and shootin' the shit, you cozy up to everyone else, watching/listening to the ping pong of conversation going on around you. Someone says something funny, and you laugh on cue with everyone else... Then it happens, that awkward moment... someone turns to you and asks in an excited voice "Ohh, did you understand?"
The feeling that you fit in shatters, you've been outed! I have no idea what they said, and in fact, you directly addressing me has shattered my thoughts of penguins riding unicorns. I didn't understand a word they said, but I understood that I should be laughing.
Years of social conditioning are not undone by a mere language barrier. I'm at work, everyone is higher on the social ladder than me, and suddenly one of them has given every social cue that they've said something funny, the head tilt, the slightly proud smile, and the twinkle in the eyes. I can't not laugh... But then someone calls you out on the fraud you are. Most likely they were sincerely excited at your sudden understanding of the new language, but your ego deflates, and you become much more fastidious with your chuckles and giggles.