A foreskin clam is the process of smegma in the foreskin becoming hardened over time, eventually resulting in a calculus bridge - like substance in the foreskin. When peeled back, the victim of the foreskin clam will pull the clam out to reveal a ring like buildup that is somewhat shaped like a clam
Foreskin clams are solid buildup is said to be more excruciating than a kidney stone