That's right. The difficulty in this case is that westcoastyvr is expressing multiple changes of thought, some of which are more closely connected than others. It'd be better to have two sentences:GordonGartrelle wrote: ↑ I wonder how this works if you want to maintain the first dash to re-instate grammatical peace. "Must have been written by a millennial - anything goes!" would work, right?
"Must have been written by a Millennial. Grammar does not apply—anything goes!"
If you really wanted it in one sentence you could use a colon to introduce a list, then separate sentiments with semicolons.
"Must have been written by a Millennial: grammar does not apply; anything goes!"
Or one could use a conjunction.
"Must have been written by a Millennial—grammar does not apply and anything goes!"
All in good fun, of course.