The abbreviation BDSM is commonly interpreted as B/D (Bondage and Discipline), D/S (Dominance and Submission), and S/M (Sadism and Masochism). BDSM play with the penis and testicles is also called Cock and Ball Torture, usually abbreviated as CBT.
The CBT practice involves inflicting pain or constrictions to the penis or testicles. Think of activities like genital piercing, hot wax play, pulling, pinching and squeezing, genital spanking and flogging, ball busting (kneeing or kicking), ball crushing, testicle stretching, urethral play, electro stimulation, or stepping on the testicles or penis.
The “victim” — typically the submissive party in the BDSM practice — may receive direct pleasure because of the pain caused, emotional pleasure through humiliation, or pleasure because the play is pleasing for the sadistic dominant party in BDSM play.
Mind that CBT needs to be done with utmost care and full consent, because many of the practices can have substantial health risks.
For instance, loss of blood flow may cause irreversible damage. Symptoms that need to be taken seriously here are numbness and bleeding in the region. Serious injuries could consist of penile or testicular rupture, testicular torsion, and testicular avulsion (a torn-off testicle), which are conditions that need urgent medical attention.