When we first heard that the fourth 'Spy Kids' film would have a "4D" title attached at the end, we naturally assumed it was a not-so-clever joke at the number of sequels in the franchise, plus the fact that this one would be in 3D. But then we discovered what that "4" really stood for: Aromascope (aka Smell-O-Vision).

When 'Spy Kids: All the Time in the World in 4D' is released on Aug. 19, viewers will get a chance to actually smell the movie. Cards loaded with eight different scents will be handed out to those attending both 2D and 3D screenings.

While we're sure that Rodriguez will make good use of this "fourth dimension," it got us thinking: What movies would we not want to smell?