Sometimes in very informal or comic book language one will see phrases such as "bonkity bonk", "flippity-flop", and "knockity knock". Other examples include "crunchity", "swirlity", etc, etc.
I have heard people add the suffix "-ity" to a number of verbs and it always seems to imply a progressive action. For example, "knockity knock" can be used to refer to the action of knocking on a door while it is still happening.
This suffix is different than "-ing" which also shows present progression. It wouldn't sound right to say "knocking knock" or "bonking bonk".
But what IS the difference? And what is the correct term for this suffix?