Hiding the two friends has risks but it can be done. There is a pocket on each side of the abdomen, just above the base of the penis. The testicles can be pushed up into the pockets, one each side, and kept there with very little pressure or discomfort, and be completely hidden. However, there is a risk of doing this for extended periods of time. The testicles need to be cool in order to perform as designed, that's why they hang in a cool sack. Tucking them up into the abdomen causes their temperature to rise, and that's when the damage can occur.
I've been tucking this way for many, many years, and as a result my testicles no longer function the way they should. I have no problem with this, and examinations have revealed that I no longer produce sperm. For myself the two friends will be gone for good soon, so the fact that I can no longer produce sperm is of no concequence to me as I don't need it.
As I said, this procedure has risks, so be extremely careful, chat with your doctor about it, that's what I did.