No pela un chango ni a mordidas
(He/she doesn't peel a monkey even by bites) •
It refers to a person not able to perform a simple task. A person who is useless, futile, or dead loss.
"Le estoy diciendo a Joel cómo preparar un lonche y sigue sin entender." "Él nomás no pela un chango ni a mordidas."
"I am telling Joel how to make a sandwich and he still doesn't understand" "He just doesn't peel a monkey even by bites."