A whip is a long, thin leather sex toy that is often used to inflict pain/pleasure upon a sex partner. Whipping is popular in the bondage, discipline, sadism, masochism (BDSM) community. Because pain releases endorphins in the brain, many people use painful sex toys like whips to intensify sexual pleasure.
A whip is operated in a swift motion where the flexible end slaps the receiving partner, often creating a sharp pain, and sometimes even mild cuts or scars, on the skin.