h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I've found (or rather, my father taught me this, we like sauce that much) that if you want to get sauce out of the bottle, use a back and forth movement, but strike your non-holding hand with the neck of the bottle at the end of the forward movement. I usually use the area between my thumb and forefinger as the target. This helps stop the bottle's forward movement and thus the sauce's inertia is more likely to push it out of the neck of the bottle. The jarring also helps break up and/or move around any thickened sauce.