What lyric do you purposely mishear?
"Evermore" from Beauty and the Beast: I once misheard "Waiting by an open door" as "Waiting by an oven door", so now I have to sing it that way
"Master of the House" from Les Mis: The way they sing "Everybody's chaperone" makes me think they're saying "Everybody's Chappell Roan"
What are some lyrics that, just to be silly, you intentionally sing different words for?