While performing “Come By Me” during a live performance, musician Harry Connick, Jr. used a clever trick to get his audience to clap along on the correct beat by adding on an extra note into a measure. By adding in this extra note, Connick, Jr. forced the audience off the first and third beats of the four-beat measure, using rhythmic displacement to guide them onto the second and fourth beats, where it should have been all along.
The video explains how clapping on 1 & 3 makes the song feels like it drags, because it matches the intensity of the notes that are played. When you clap on 2 & 4, though, that intensity is more even throughout the song and so it feels like it flows better rather than a stop-and-go type of feel.
A different explanation of the same process.