See: COME ON(3).
. To meet accidentally; encounter; find. * /He came on an old friend that day when he visited his club./ * /He came upon an interesting idea in reading about the French Revolution./ Syn.: COME ACROSS, HAPPEN ON. 4. {informal} Let's get started; let's get going; don't delay; don't wait. - Used as a command. * /"Come on, or we'll he late," said Joe, but Lou still waited./ 5. {informal} Please do it! - Used in begging someone to do something. * /Sing us just one song, Jane, come on!/ * /Come on, Laura, you can tell me. I won't tell anybody./