There are two theories about the origin of this expression. There was an acient custom, in times of Alfonso VII (1104-1157), extended in Castilla y León, Navarra and Aragón, which took place at festivals, where several pigs were released in a square or a ring, so that blindfolded men, protected with helmets and armed with sticks, tried to chase and beat the animals to death, keeping the corpse as a prize. Since they were blindfolded, in their quest to win the prize, many times failed to hit the animal and some other times they even hit other blind people, making the audience laugh.
A modern version, less cruel than the medieval, is what today we know as piñata, game in which blinfolded people armed with a stick must break some earthen pots hanging from a rope and filled with treats and sweets. As in the medieval version, the player must take several shots into the air before hitting its target.
Nowadays, we can use this expression in different contexts. We can use this expression for those people who don't have very clear their purpose in life and they stagger through it.
Acabas de perder tu segundo trabajo en dos meses. Tu mujer se quiere separar de ti y además no tienes ahorros. ¡Sólo das palos de ciego en esta vida!
You just got fired from your second job in two months. Your wife wants the divorce and you don't have any savings. You're flying blind in this life!
Or can simply use this expression to talk about a person who, in a particular subject, doesn't have very clear what guidelines must follow.
Para resolver bien este test de matemáticas, primero, léete la lección. Después, haz los ejercicios del libro y ya por último, resuelve el test. Si no, ¡no pararás de dar palos de ciego!
To solve this Math test, first, read the lesson. Then, do all the exercises in the book, and lastly, take the test. Otherwise, you'll keep doing blind attempts!
Sometimes, in a delicate issue, some people proceed aimslessly, creating an unwanted situation. This expression can be used to signify the damage suffered to proceed without tact or caution.
¡No voy a ir a la conferencia a dar palos de ciego! Voy a prepararme bien el tema y entonces asistiré, pero no sin habérmelo preparado bien.
I'm not going to the conference to fly blind. I'll prepare very well the topic and then I will go, but not without being ready for it.¡Estamos dando palos de ciego! Creo que no es así como el profesor quiere que hagamos el trabajo en grupo. Vamos a establecer unas pautas.
We're taking shot in the dark! I think this is not the way the professor wants us to do the group assignment. Let's establish some guidelines.
More examples:
Como no sabía cómo funcionaba la máquina empezó a dar palos de ciego con los botones.
Since he didn't know how the machine worked, he randomly started pushing all the buttons on it.
El presidente de la oposición acusó al Gobierno de estar dando palos de ciego en el asunto de la inmigración.
The chairman of the opposition accused the Government to be flying blind on inmigration issues.
Los concursantes de esta semana no paran de dar palos de ciego. ¡No están acertando ni una sola respuesta correcta!
This week's contestants can't stop taking shots in the dark. They are not hitting a single correct answer!