I'm about 2 1/2 or 3 weeks into using Testim 1% testosterone gel and thought I'd give it a try on my balls, so here is a very non-technical account of my experience...
I was prescribed Viagra for ED, but after my last blood test my Doctor noted that I had extremely low to what he described as almost non-existent testosterone levels he started me on Testim gel tubes. I had two reactions really, the first was unpleasant and the second more like a level reaction with all good side effects, but I didn't try the the scrotal application until the negative effects of the first week leveled off and went away.
Week one I felt pretty irritable and aggressive compared to my mild mannered self, or was I acting normal rather than too passive because of low-t? Anyhow it only lasted one day that was really bad, I skipped a day and that was the end of that that then and it gave me an extra tube on hand.
After that it's been great! I have more energy and my mood is good and energetic rather than irritable and aggressive. I tried it on my scrotum using that extra tube I had from the skipped day, but only used about a quarter of it there. The effect I got was very evident within about a half hour as I had a thicker than normal penis that, for the first time in years, was hard enough to penetrate both with my wife (after a good shower of course) easily. We were exhausted the next day
Two days later I tried it again (Friday night is our wild sex night, the rest of the week is anything goes but Friday is when we allow each other to do whatever we want), but also used a Viagra to see what would happen. I don't care what anyone says, that was the best sex I've ever had!
We didn't go to bed until about 6am,
I'm just starting to come back round, and we're both just smiling and giggling at each other today. So take it for what's it worth, that has been my experience minus the scientific or medical jaw.