I've never heard of a "Slam Cut." Perhaps you mean SMASH CUT.
From Wikipedia
A smash cut is technique in film and other moving visual media where one scene abruptly cuts to another without transition, usually meant to startle the audience. To this end, the smash cut usually occurs at a crucial moment in a scene where a cut would not be expected. To heighten the impact of the cut, a disparity in the type of scene on either side of the cut is often present, going from a fast-paced frenzied scene to a tranquil one, or going from a tense scene to a pleasant one, for example. Sometimes it is also used to transition from the more peaceful scene.
An example of a clichéd smash cut is in a murder scene; a knife is raised, and thrust down, with a smash cut right when impact is expected. Smash cuts are often used when a character wakes up from a nightmare, to simulate the jarring nature of that event.
This technique has been used frequently in many of the opening sequences of The West Wing and in many episodes of Lost.
