Most men fail to complete the vasectomy process. To make sure the surgery has shut off their sperm supply, they're supposed to submit two follow-up semen samples. In a previous study, half the patients didn't submit the second sample, and a quarter didn't even submit the first.

In a new study, only two-thirds who were left to schedule their own follow-up appointments submitted a sample, and only 20 percent submitted a second sample as instructed. Scheduling the appointment for them raised the compliance rate to 84 percent for the first sample and nearly 50 percent for the second.

Researchers' conclusion: "Asking men to submit two sperm-free samples may be overly demanding."

Translation: Men are so lame at follow-through, you can't even get them to jerk off.