having never told a lie
A jocular set phrase playing on the homophony of 言う (to say) and 結う (to tie up, do up hair). Literally 'a lie and a monk's head have never been tied up', meaning 'I have never told a lie' because a monk's bald head cannot be tied up, just as a lie cannot be 'tied' (said). Used humorously to claim one has never lied.
My old man used to say, 'I've never told a lie,' with that pun about a monk's head.
The verb 'to say', which is homophonous with 結う in this phrase, creating the pun.
The verb 'to tie up' or 'to do up hair', used in the pun to mean 'to tell a lie' by association with 言う.
A humorous pun based on the homophony of 言う (iu, to say) and 結う (yuu, to tie up). The phrase literally means 'a lie and a monk's head have never been tied up', implying that just as a monk's bald head cannot be tied, a lie has never been 'tied' (said).