In prison, inmates are often surrounded by individuals who have engaged in criminal behavior, and they may learn new tactics or strategies from their fellow prisoners to improve their criminal skills. This can perpetuate a cycle of criminal behavior within the prison system as individuals share their knowledge and experiences with one another.
Carbohydrate, Fat, Protien, & Nucleic Acid:) Your Welcome, Fellos.
The plural noun is spelled "fellows" (peers, guys).The slang term is spelled fellas.