Sitz Bath:
A sitz bath is a warm water bath you sit in to relieve discomfort in your perineal region. Soaking this area in warm water relaxes your anal sphincter, which helps increase blood flow through your anal tissues. This promotes healing and reduces the pain, itching and irritation felt due to various health conditions. [Cleveland Clinic]
For a visual, you can sit through this video from the Our Restoration Nation folks. The mention and visuals is roughly here.
