My pleasure. "コーヒーを入れる" is a fixed phrase that you usually say when you mean "make coffee".

@Ueda Thanks for your explanation. Now I can understand the whole conversation. You are so nice!

It is not clear because he is talking with the other while brushing his teeth, though I guess from the context that he is saying "じぶんでいれろ", which means "Make coffee by yourself".

＠Ueda I added more information to my question. Is that should be 「じぶでやれろ」in this conversation？

Your sentence doesn't make sense. You had better make sure you copied the original one correctly.