 In the very first show, OBrien jogged out from behind the curtains  to his mark for the opening monologue. As time went on, he would try  new things (in one show, he just jumped up and down to his mark).  Eventually, he adopted this "shuffle", where he would walk hunched  over and have his arms shuffling at his sides. When the show  returned to air for the first time after the terrorist attacks on  the USA of 11 September 2001, he replaced the shuffle with a more  subdued walk, which he continues to use today for his entrance.