Self-abuse and self-pollution  were common in early modern times and are still found in modern dictionaries. It could be caused by a low-grade urinary tract or yeast infection, or the child may be overstimulated and in need of soothing, or indeed understimulated and bored. Individuals of some species have been known to create tools for masturbation purposes.
i.d like to lick that red pussy
She looks good attached to the end of that hog. Hope her husband realizes he should have been more attentive to her.