CBT stands for "Cock and Ball Torture". Torture can be inflicted by: Slapping, Squeezing, Pinching, Weights/Parachutes. The testicles can stand great pain but caution should be taken.
In some cases, "Torture" is considered "Play". The testicles are simply tugged on or stretched out.
Most men find handling, stroking and squeezing gently is a pleasurable sensation. Some enjoy using ball stretchers to achieve a longer sac.
Girl: "His balls are so long! They slap against my ass all the time, I love it."