Cuando esta piensa ( points to crotch area)
Esta no piensa (points to head/brain)
This basically means that when we let our sexual urges control us, we lose all cognitive reason. Mothers say this to their daughters in order to explain to them the consequences of getting caught up in sexual urges. My informant overheard his wife saying this to his daughters.
My informant is a building engineer. He migrated to the United States form El Salvador when he was 16 years old. He grew up in a city in El Salvador. Lots of the folklore he has heard has come from his family.
This proverb is an excellent example of the taboo nature of sexual relations are in the Salvadoran culture. There is this sense of preventing from the relations to happen versus acknowledging and offering support.