Theres so much misunderstanding on this one. Like its some super-taboo to put Testosterone on the bally bag when its been done forever. I see post after post of bros using it as a punchline. While I understand the very idea of swathing the Kiwi fruit with anabolic gel is somewhat humerous, lets talk seriously for a second.
Its not dangerous. Scrotal application is by far the most effective for transdermal drug delivery, easily achieving over 50% absorption (widely accepted at up to 70% with the right carrier). When choosing a formula, make sure it does not have a large % of alcohol because that is what is the main source of discomfort for the nuts. There is at least one cream specifically designed for this, Andromen Forte 5%, so its nothing new.
The scrotum has a very high % of 5-alpha reductase enzyme so DHT conversion is high and can have a very negative impact on the prostate. Ancilleries should be used such as divanil (nettle root), saw palmetto, etc. At worst Propecia.
Finally, Testim sucks balls (no pun intended). But, if you could stand it on the balls it would be much more effective. Depending on how much you have, I would have an AI or SERM on hand. Don't expect it to be like injecting 500mg of Sustanon 250 though.