Is there a tag for the "fall over instantly after something dumb happens" gag?

something like the last panel in post #2088327.

i feel like faceplant is probably the closest one but it obviously doesn't cover the use of the gag when they fall over on their back. besides it looks like faceplant's more used for tripping over something and falling over in a "realistic" manner.

The Japanese term ”zukkoke” / "zukkokeru" is often idiomatically used to describe that manga expression technique. The word's original meanings are listed here.
Some onomatopoeias are also associated with it, but sometimes they can be misleading. For example the onomatopoeia "zukoo" is often used for this ascii-art pose.

This?

http://tvtropes.org/pmwiki/pmwiki.php/Main/FaceFault

Kinda strange there is no such tag here yet.