Climacturia is a medical term describing orgasm-associated incontinence, or the experience of leaking urine at the moment of orgasm.
While it is a relatively recent term to appear in the medical literature (first appearing around 2005) it is thought to be a relatively common result of radical prostatectomy -- the removal of the prostate as treatment for prostate cancer.
There is variation in how often it happens and how much urine is passed during orgasm. The likelihood of climacturia may relate to the type of procedure and type of cancer, although there isn't a lot of research on the topic.
In a 2006 study of 42 men, two years following radical prostatectomy, 68% reported experiencing climacteria. Forty-eight percent felt that it was a significant bother to them. In a 2007 study of 475 patients, 20% reported climacturia following radical pelvic surgery. Men were more likely to experience it in the first twelve months following surgery than later.
Common ways of dealing with climacturia mentioned in the studies included emptying your bladder before sex and wearing a condom during sex.
Choi, J.M., Nelson, C.J., Stasi, J., Mulhall, J.P. "Orgasm Associated Incontinence (Climacturia) Following Radical Pelvic Surgery: Rates of Occurrence and Predictors". Journal of Urology Vol. 177 (2007): 2223-2226.
Lee, J. Hersey, K., Lee, C.T., Fleshner, N. "Climacturia Following Radical Prostatectomy: Prevalence and Risk Factors" Journal of Urology Vol. 176 (2006): 2562-2565.