When the doctor returns, he asks Jack to lend him some equipment so that he can conduct experiments on it. Jack says he'll do it, but he's not sure what the purpose of the experiment is. He's worried that the doctor will come back and tell him that it's Christmas Eve, and he wants to do something before the doctor does. He asks the doctor if he can come out and do something, and the doctor says he can, and Jack says that's all he can do. The doctor asks Jack if he'd like to come out, but Jack says no, and then the doctor comes back and tells Jack that he needs to borrow some more equipment. Jack is all, "I'm home, I'm doing experiments" , but the doctor doesn't seem to understand what's going on. He says that Jack should come out now and perform some experiments. Jack's like, "Gee, I need to do this before he comes back" . He tells the doctor to come back out and perform a few more experiments, and they start to sing Jingle Bell Rock. Jack can't figure out what this is all about, so the doctor asks him if he would like to do some more. Jack agrees to do so, but says that he has to hurry up and finish the experiments before he can leave. He gives the doctor a piece of paper to scribble on, and says that if he promises to behave, the doctor can come in and perform the experiment. He then asks if the doctor has come back yet, and if so, Jack says, "Go ahead and do it." The doctor comes out and asks if Jack can do the experiment, and when Jack says yes, he says that it would be a good idea if he came out and performed the experiment before he left. Then the doctor leaves. Jack asks if he could come back in and do the same