The combination of "fantastic", "fabulous", and "ballsy." If someone describes you as fantabuballs, you are truly amazing in all from and sense.
Joe: Man, you look fantabuballs today!
Tim: Thanks dude! It's going to be a fantabuballs day, gotta dress for the occasion!
Tim: Thanks dude! It's going to be a fantabuballs day, gotta dress for the occasion!
by Patron Saint of Lost Causes August 19, 2013