I recently learned some important information for men. It appears, from various sources I scouted and first learned from reddit, that a pregnancy test turning positive for a man may indicate the presence of testicular cancer. The reason is that pregnancy tests work by detecting the hormone human chorionic gonadotropin (hCG), present in urine and blood after conception. The same hormone is also present in the urine when some types of cancers are developing, therefore the presence of a positive result in men may indicate presence of these types of cancer, most often found in testicular cancer.
Now, I am not a medical doctor, but a quick search on google scholar led me to this paper, where indeed hCG is considered a viable marker for testicular cancer. Wikipedia seems to be a reliable source on this regard, and according to what I found on the web, it's reasonable for me to say that indeed a pregnancy test can be used by a man to assess a potential testicular cancer. Like any other medical evaluation, it must however always be confirmed with additional checks.
I welcome comments or corrections on this regard.