"I'll be there with bells on" is a common English idiom meaning that one is excited to arrive at, and take part in, an activity or event, and will most certainly be there. It is sometimes also used to indicate speed, as one would hurry to an exciting event.

'With bells on' is an annoying phrase in that it is well-known, it clearly appeared in the United States of America in the early 1900s, and has no even remotely reliable etymology. Bells have long been popular adornments of Morris dancers and jesters, hawks and horses, and there are any number of possible reasons some rando in 1904 California might have decided to use the phrase to describe a local boxing match ("Jeff will without doubt be in good condition by the last of the month and barring further accidents will be there with bells on" - Oakland Tribune, June 1904). Following that obscure first appearance, American publications started using the phrase infrequently but with the full confidence that everyone would know what they meant.

There are approximately umpteen-million cultural references to bells of all sorts and types that could give rise to references of happiness, excitement, celebration, and silliness. There are also related phrases such as the English with knobs on (meaning 'to have unnecessary ornament') and the American counterpart with brass fittings. It is almost certainly the case that Americans just like saying slightly silly and slangish things, and all tales of it being a clear reference to jingle-bells, settlers paying rescuers with bells, or Jewish high priests (because they wear bells, that's why) are just the sad wishes of those who want every colorful phrase to have a colorful origin story.