notadictionary.com
元カラオケ店員私の史上最悪の言い間違い絶対これ。
→ “As a former karaoke staff member, this is definitely the worst wording mistake of my entire life.”
元 moto = former / original (adjective/noun prefix)
カラオケ karaoke = karaoke (loanword noun)
店員 ten'in = staff member / clerk (noun)
店 miya = shop / store
員 in = member / person
私 watashi = I / me (pronoun)
史上 shijō¹ = historical record / history (noun)
史 shi = history / records
上 jō¹ = on / above
最悪 saiaku = worst / most evil (adjective/noun)
最 sai = most / utmost
悪 aku = bad / evil
の no = 's / of (possessive particle)
言い ii = speaking / saying (verb stem)
言 i = say / speak
い i = speech (nominative form)
間違い machigai = mistake / error (noun)
間違 machiga = to err / to be wrong
え e = result / state (suffix)
絶対 zettai = absolute / definitely (adverb/adjective)
絶 zetsu = cut off / stop
対 tai = opposite / pair
これ kore = this (pronoun)