What's the joke about the rabbit getting lost in the forest?

There is a little white rabbit going somewhere, but he got lost at a crossroads in the forest. He happened to see a little black rabbit and asked him for directions. The little black rabbit said, I can tell you, but you have to make me happy. The little white rabbit thought about it and agreed. After that, he moved on. When he reached another intersection, he still didn't know how to get there. At this time, a little gray rabbit came, so the little white rabbit asked him the way, and the little gray rabbit also offered to be happy with him, and then told him. The white rabbit agreed again, and then walked on, but met a fork in the road. At the same time, a little yellow rabbit came over and asked for directions. The little yellow rabbit made the same request, and the little white rabbit agreed. By the time he reached his destination, the white rabbit was pregnant and gave birth to a bunch of rabbits.

Excuse me, what color are these rabbits?

Answer: I will tell you if you want to make me happy ~