The informant is a first generation Mexican-American student. She said that she spends a decent amount of time in Mexico still (she usually visits a couple weekends during the school year and goes for slightly longer periods during the summer). She visits a lot of family in Mexico, including her grandma, a lot of cousins, and aunts and uncles. She learned this proverb from one of her uncles during these visits.
The informant said that the first time she remembers hearing this proverb is when she was a young child and was talking incessantly about pokemon. Her uncle said it to her and she said he essentially meant, “shut up, kid.” Since then, she says that she and others use it to let someone know they are being too long-winded.
En boca cerrada, no entran moscas
In a closed mouth, flies do not enter.
The informant found this proverb very funny and she seemed eager to pass it on to me, so that she can now say it to me in Spanish and I’ll know what it means, even though I don’t speak Spanish. I think she desires to perform this proverb so badly because it allows her to say something kind of rude to the people she cares about, but in a playful way, so that it is hard for the person to get mad. She also seems to use it to identify with her Mexican roots and her close connection with her family in Mexico. This is something they apparently all say to each other.