To put it clinically, cock and ball torture (abbreviated as CBT, but also known as penis torture or dick torture) is a sexual activity that involves constriction to the penis or testicles, or the application of pain to the genitals, with the aim of heightened pleasure. The umbrella of cock and ball torture actually covers all kinds of kinky restraint and sensation play when done on the penis and testicles
But, if you’re not a fan of the word ‘torture’ - although it means something entirely different in the BDSM world - it’s perfectly fine to call it ‘cock and ball play’.