wedding bells

why do people say "do i hear wedding bells??" when they think someone is about to get married?? i just asked my friend and i said, "do i smell wedding cake??" i think this is much more appropriate since i dont actually have any memory of bells at weddings. even if there ARE bells at weddings...is that what people really remember or think about?? i dont think so. i think that expression should change. do i smell wedding cake?? could def be a contender for its replacement. right??