Basically, just the process of putting something large into your genitals. Be that dildos, plugs or any other kind of sex toys, or even a large penis / some other kind of object.
Be Careful What You Wish for by Mikel
Be Careful What You Wish for by Mikel (Archive Link) Really old story by Mikel from 2013 detailing Judy’s obsession with corsets and chastity, often wearing a combination of the two under her work clothes. She soon orders a specialized corset for long-term wear, that goes far beyond what she initially had imagined. When she finds out that the control unit of her specialized version has a software bug, she finds herself locked in her new outfit for quite a long time. ...