Eager; ready to participate. (Oh.... and I am VERY EAGER)
This phrase is frequently used in reply to a party invitation and the common format in that case is to indicate one's enthusiasm with 'I'll be there with bells on!'. The phrase originated in the late 19th/early 20th centuries and most of the early citations of it suggest a US origin. The first record of it that I have found in print, which I doubt is the earliest usage, is in F. Scott Fitzgerald's The Beautiful and the Damned, 1922: "All-ll-ll righty. I'll be there with bells!"
VAMIKEY.....you probably already knew that bit of trivia