Your brain is always trying to synchronize the sensory information that it receives so that things make sense to you. For example, if you touch your heel and your nose at the same time, you don't feel the touch at different times, despite the fact that it takes longer for the electrical impulse to go from the heel to the brain, than the nose to the brain. What your brain does is delay its perception of time so that you feel the touch at the same time. Now, touch signals travel at about 76 meters per second. The moon is 363,300 kilometers away. If his dick reaches halfway to the moon, the head is 181,650 kilometers away. That's 181,650,000 meters away. So that means that it would take about 2,390,132 seconds for the electrical impulse to reach his brain which is about about 39,836 hours. That comes out to about 1,660 days, which is about 4 and a half years. Now, let's take the brain delay information from above. If anything, even something as small as a mosquito landing on him happens at the same time as the astronaut stripper makes her attempt to rub up on his spacedick, his brain will delay that feeling so that it matches up with whatever other thing touched him. Thus, about 4 and a half years of his life will have passed without his knowledge.

I'm bad with math. If anybody wants to check this on their own, corrections would be appreciated.