What does this joke mean? What's your name? Then I'll rub your mother's feet. Which sentence is it?

My sister called to complain: "A friend came to visit and I sent a plush doll to her daughter's house. As a result, your brother-in-law lost his temper when he came back from work, saying that the plush doll was a gift from him and should not be given away because he devoted himself wholeheartedly. Now, I have the cheek to get it back. "

I joked, "Haha, maybe he hid his private money in the doll."

After a while, I actually received a 200 yuan red envelope from my sister. The message said: Good brothers!