Circumcision is anti-sex.

This article in The New York Times led me to this study, Fine touch pressure thresholds in the adult penis.

The relevant conclusions?

The glans of the circumcised penis is less sensitive to fine touch than the glans of the uncircumcised penis. The transitional region from the external to the internal prepuce is the most sensitive region of the uncircumcised penis and more sensitive than the most sensitive region of the circumcised penis. Circumcision ablates the most sensitive parts of the penis.

Oh yeah, and this:

Whether the penis is circumcised or not might also affect coitus. For women, having a male partner with a foreskin increased the duration and comfort of coitus and increased the likelihood of achieving single and multiple orgasms