“For today’s prompt, I want you to write a sestina…  So start figuring out your 6 end words and get writing.

“But wait! Today is Tuesday, so you have one other option. You can write a poem about the sestina (your love, hate, frustration with, etc.).”

This is a terrible poem – I’m warning you now!  🙂  I am completely undone at the idea of writing a sestina off-the-cuff;  it is a poem that takes a lot of thought and is constrained by a certain format.  So I just whine a while, and call it a poem.  Someday soon, I will write a sestina, but it won’t be today!
“Write a sestina,” he says,
and I stare at him, astonished.
A sestina is a project,
not something I can dash off
in between Tuesday chores!
First there’s the math, not my
strong point:  six lines per stanza for
six stanzas, then a seventh with
only three lines;  my head spins, thinking
of thirty-nine lines, complicated by
six words.  Choose them well, for one will
end each line, juggled ‘round in order,
until stanza seven, where two by two,
they end it all.  There is a plan –
the sestina’s only saving grace –
but you must plan to use the plan!
My brain goggles at the very
idea:  a sestina, on a Tuesday!
(Goggling, of course, is the first
barrier to writing such a poem.)
Too much to compute, too hard a
pursuit. I need a week, perhaps two!