Obviously, by looking at the bride and groom, this is a sign of respect. Downright scary to the uninitiated.Some years ago worked with a bunch of kiwis (New Zealanders). After a few drinks at the weekend they would entertain us with a haka which eventually we learned. In a Glasgow pub some arsehole would get out of order, a glance around us would kick off a haka and that would put his gas at a peep as we say here. A war dance that didn't end up in violence is a winner.