Per the jQuery docs, calling removeClass() with no arguments should remove all classes:
If a class name is included as a parameter, then only that class will be removed from the set of matched elements. If no class names are specified in the parameter, all classes will be removed.
However with the regexp monkey-patch in place, this gets broken:
$('body').removeClass(); // doesn't remove anything!
Changing line 19 from call to apply fixes the zero-argument case:
removeClass.apply(this, arguments);