This is something to keep in mind since there is no effective way to heimlich oneself. Animals do this in order to clear their airway. Hopefully this is something you'll never have to use first hand. It's a good thing to just know. Statistically speaking, the odds are greater for encountering a partially obstructed victim than a complete.
Complete obstructions are the scary ones.
You may see them put their own hands to their neck in some universal sign of choking. Their face begins to discolor, red to purple to blue. They can't make any air exchange at all. Partial obstructions aren't life threatening normally. It works its self out by our own natural responses.