A schoolie is an adult who ageplays the role of a schoolboy or schoolgirl (see also adult child). Typically their partner plays the role of their guardian figure, such as a teacher or parent. This allows for a wide range of possible punishment scenes that are based on stereotypical adult/schoolchild interaction, especially those stricter methods that were once common in the past.
Teacher with blackboard pointer in c. 1930s spanking photo.
Japanese dancer in sailor suit style school uniform.
Transvestite in a schoolgirl-style tartan skirt.
In a PE kit (aka school uniform)
waiting on a chair before being taken over the knee