This is the slogan of the Humane Society of PR and can be translated roughly, "we're all orphans". Sato is the word for a mixed breed dog as well as an abandoned dog, obviously more the idea in this phrase. The idea seems to be, since we're all misfits, or really all imperfect, they we should take pity on a dog who is not "purebred" too.
This phrase seems to me to be very applicable to us as Christians and our relationships with others. Too often we look down on people in the world as "inferior" because "can't they understand the Bible?" or "they don't try to resist sin", etc. When we pause to remember that we also sin, then we can have more compassion on them. They are still in sin and the wages of sin is still death, but instead of condemning them as ungodly, we should rather see them as our Savior did, as sheep without a shepherd, needing someone to guide them. Remember "todos somos satos"--we all sin and all need God's forgiveness.
The same is true of brethren whom we view as "sinners", whether it's because they're weak and fall short often or whether it's brethren who we view as strong, who commit a "big" sin (big in our eyes--we know God views all sin as damning). While we cannot tolerate or encourage sin, we can recognize that we also are human and can fall. We can "restore such a one in the spirit of meekness". "Todos somos satos".
Our Lord's attitude when dealing with sinners should be instructive. When confronted with a woman who had had 5 husbands Jesus was gentle, patiently teaching her, even though she "didn't get it". When presented with a woman taken in the very act of adultery, rather than condemn her, Jesus forgave her and cautioned her to sin no more. He knew her heart and knew her repentance: we can't read minds, so we should take people at their word until they show us otherwise. On the other hand Jesus condemned the Pharisees harshly and on more than one occasion--since in their own eyes they were guiltless they had no patience with "the people".
So the next time you are ready to recoil from a "sinner", whether a Christian or not, remember "todos somos satos".