Ask what words mean. Exploring the sensitivity of your sphincter is an exercise both you and your partner can enjoy prior to penetration. Here is a resource to help you find STI testing centers. Spend time safely exploring the sensitivity of your sphincter and how it reacts when you are relaxed or tense. Reading this article made me feel alienated as a gay man, and I think it lacks the depth you think it has. Thanks to a culture that is and always will be hetero-oriented, queer people are often delayed. I promise.
The sphincter muscle is a sensitive membrane with many nerve endings and thus the source of pleasure or pain. Follow Thought Catalog. It hurts, it feels good, it feels wrong, it feels right.
Pain associated with anal sex can be due to pressure or friction against the sphincter muscles, hemorrhoids or anal fissures.