Every year there's a "Stanley and Stella" shouting contest in conjunction with the Tennessee Williams/New Orleans Literary Festival. This was what I found on it:

Mar 28 - Apr 1

Tennessee Williams/New Orleans Literary Festival
New Orleans, Le Petit Theatre du Vieux Carre, 616 St. Peter St., the Cabildo, Historic New Orleans Collection and other venues to be determined. 504-581-1144
http://www.tennesseewilliams.net/
Theater, literary events, music, film screenings, book fair, walking tours and "Stanley and Stella" shouting contest. 20th anniversary.

You can see the 20th anniversary version here:
http://www.youtube.com/watch?v=cAP9f_GJQxI

Note the walkie-talkies instead of shotguns at 1:14