HORSECOUNTING 

When an individual reaches the top of a set of stairs only to incorrectly think that another step requires surmounting, the resulting leg movement that then arcs upwards and outwards could be said to resemble the manner similar to that of a horse when counting with a foreleg.

Just walked up to level 2 and caught some serious air horsecounting as I arrived

HORSECOUNTING by zebraboy777 September 10, 2010