Edit in JSFiddle

//extend the A object with Backbone.Events methods
var A = _.extend({name:'A'}, Backbone.Events);

var foo = function () {
    console.log('foo');
};

A.on('log1',foo);
A.on('log2',foo);

A.trigger('log1 log2'); //logs foo then foo
A.off(null,foo); //remove foo callback from all events
A.trigger('log1 log2'); //logs nothing, all foo callbacks have been removed