Two other readings exist. Toneless
喔 is a Taiwan-flavored sentence-final particle that softens a correction or gentle admonishment (
小心 一点 喔 = 'do be careful, ok?'). And
喔 (first tone) is onomatopoeia for a rooster's crow, almost always reduplicated as
喔喔 — the Chinese equivalent of 'cock-a-doodle-doo'.