I.out [美 aʊt, 英 aʊt]副out often appears as the second element of certain verb structures in English (come out, keep out, knock out, etc). For translations, see the relevant verb entry (come, keep, knock, etc).
There are generally two reasons for this: either they punch so hard, the promoters of prospective champions want to avoid them; or, they stink out venues because of their styles.