He thought about why that would be and then realized why rather quickly. Water and spit would absorb into the skin quickly or dry too rapidly. It wouldn't be helpful for the preparation. However, oil could be good because it absorbed slower and allowed for more flexibility. Such as when one oiled leather to make it move better. That was honestly very reasonable.

It was interesting that a woman's body did lubricate though. But he understood that wasn't necessary information for him when his boyfriend was very obviously male.

Oh. Another question he had... "Wanyin-qianbei, how do you know how the penetrating partner is with two men? It seems clear with a man and a woman but not so clear with two men. Is there a way to tell?"