Irony In A Mangled Cliche

From this Yahoo! article about shoplifting pregnancy tests, we get this line:

Many little boxes can be stuffed quickly into a bag in one fail swoop.


Um, yeah.  I'd call it a "fail," too, when you can't even get a cliché right.  *rolls eyes*  It's "one fell swoop."  Duh.
That's not even a mixed metaphor; it's just dumb.
But it IS irony.