one of the boys
An accepted member of a particular social group, especially one made up primarily or entirely of men. Primarily heard in US. John's a nice guy and all, but he just never seemed like one of the boys. As a woman working in this industry, you have to both be one of the boys and still be seen distinctly as a lady.
one of the boys
COMMON If you describe someone as one of the boys, you mean that they are accepted as belonging to a group of men who behave in typically masculine ways. His overly enthusiastic efforts to seem just one of the boys were sometimes embarrassing. If she played at being one of the boys she was condemned for being unwomanly. If she didn't join in she was seen as aloof. Compare with one of the lads.
one of the boys
accepted by a group of men.