The prison officers know what they are going to receive before they actually clap eyes on new prisoners. They know the lads age, ethnicity and what hes down for. You want to make sure that any tasty new piece of meat is checked over thoroughly before dishing it out to the sex-hungry prisoners on the wing. Now a young lad being sent down for the first time is going to have the older lags queuing up to take advantage of it. Apart from checking its orifices for contraband the screws will also want to check its holes for other reasons!