What is most likely purpose of Shaw having Higgins say the following line?"Oh, chuck them over the bannisters into the hall. She'll find them there in the morning and put them away all right. She'll think we were drunk

It does a couple of things. It makes the audience laugh. It is a pretty funny line. [ It also shows Higgins character as intelligent (he has the situation figured out), arrogant (he is concerned with his own convenience), and inconsiderate (he is not worried about imposing on anyone else.