Red heart bra or pants spiky insert
A red pair of plastic disks, slightly curved, with sharp plastic spikes on the inside. Designed to sit inside the bra or pants, to add a level of discomfort during the day. The spikes are sharp enough to be noticeable, and will really dig in if they are pressed or spanked.
Choose from a plain red, which will be slightly more discrete under clothing if they are for daytime wear, or a heart symbol back.