Can a so-called friend have your wages garnished even though the person has nothing in writing that a personal loan was made?

Can a so-called friend have your wages garnished even though the person has nothing in writing that a personal loan was made?If they go to court and get a judgement against you... then yes.

All they have to do is convince the court to ITS standards of proof.

A garnishment is a court order. So it requires a judgment in court to issue one. A personal loan can be proven other than by a note, but its not easy.