BAD SPELLERS OF THE WORLD UNTIE!!!

While spellcheckers are ubiquitous, the inclination to use them is apparently not. I personally appreciate and advocate individuality and originality in general, and if one is creatively inspired to rail against the illogical, if steadfast, rules of English spelling, then all power to them, but please, in order to willfully deviate in a conscionable and responsible manner, musn't one first know from whenst they might have begun?

Spell this, you motherflappers!

Hey, why is my spellchecker underlining "whenst" and "musn't"?