pendejo is a Spanish word that means (at least in Mexico), "idiot", "dolt", "imbecile". For example: "Ese pendejo se me cruzó y choqué con el pesero" - "that idiot cut me off, and I crashed with the pesero."
To my knowledge (and differently from cabrón) it can't be used as a "friendly" insult.
pendejos do pendejadas, that's to say stupid things.

nodeshell no more!