Read on Twitter
Come on, people! There's no "p" in whomstever. https://twitter.com/bestofnextdoor/status/1385071383642664964
Not in the spelling, anyway. There may be an epenthetic [p] (that is, one that is inserted for pronunciation reasons), because when you open your lips to switch from the [m] to the following [s], you might release a little puff of air, which is all a [p] really is.
In conclusion, "whompstever" is an interesting collision of somewhat formal-sounding morphology (the "m" on "whom"), rather archaic-sounding morphology ("-ever"), deliberately silly morphology ("-st"), and a rather normal phonetic process.
Lest we forget one of the original viral websites and a great example of an epenthetic [p]. https://twitter.com/IvaCheung/status/1385087964980539394?s=19
