“No Tener Pantalones” (Not having pants on)
It refers to humiliating yourself, shamefully giving in to someone’s unfair claims, despite being right or having acted correctly. Someone is said to not have pants on when he accepts conditions that are unfavorable to him or when pressure or fear causes them to give themselves up for good positions to which they had been contrary. In other words, being a coward.
“Bajarse los Pantalones” (Lower your pants)
The reference to pants as a symbol of masculinity or virility, in short, of power, seems clear. But whoever has his pants down is about to let others abuse him, in the harshest sense of the word. In a business context, it is to give in on a dishonorable negotiation. If someone has lowered his pants when he accepts conditions that are unfavorable to him.
“Amarrarse los Pantalones” (Tying the Pants)
It means that you have to do things responsibly and fill yourself with courage, leave all fear behind to work harder to get what you want; demanding all abuse and malpractice must end. It can also be said like “Amarrase el Cinturon” (Tying your belt).
“Tener los Pantalones Bien Puestos” (Carrying your pants well put or adjusted)
Wearing pants means being in command, being the boss, the one who gives orders, the one with power, and the one who says the last word. It is often used a lot when talking about who is the decision-maker in a family. For example, imagine that the decision-maker in the house is the woman (the wife, the housewife). In that case, it is said that she is the one who wears the pants, although she is always actually dressed in a skirt and is very feminine, to refer to her power in the house, she is said to wear the pants.
So now you know these popular expressions in our country. Remember when you visit and are practicing your Spanish, be careful what you say, as to not be misinterpreted!