If a guy was not circumcised as a child, can he get it done in adulthood?

Yes,but: While the process is simple & quick as a newborn it becomes a problem as an adult. Newborns can be done awake under a local anesthetic with a simple clamp device. Adults generally require a general anesthesia & suturing. As i recall it was one of the most requested forms of requested elective surgery during my time at a naval medical center.