Although the phrase is used in connection to Estragon's boots here, it is also later used by Vladimir with respect to his hat.The difficulty for Beckett of keeping a dialogue running for so long is overcome by making his characters forget everything.And since Vladimir cannot rely on Estragon to remind him of things, he too exists in a state of forgetfulness.Essentially it describes the hopelessness of their lives.Thus, most of the play is dedicated to devising games which will help them pass the time.Since passing the time is their mutual occupation, Estragon struggles to find games to help them accomplish their goal.Thus they engage in insulting one another and in asking each other questions.Vladimir, although possessing a better memory, distrusts what he remembers.