The phrase refers to the act of simulating sexual intercourse with a pillow. This behavior is typically associated with adolescents or individuals exploring their sexuality. Examples include rhythmic thrusting motions against the pillow, often while lying prone.
Understanding motivations behind such actions can offer insight into developmental stages, coping mechanisms, or potentially indicate a need for sexual education and healthy exploration outlets. Historically, this practice might have been viewed with varying degrees of acceptance depending on cultural norms and societal views on sexuality.