“A Malleable Metrical Mastic”

A malleable metrical mastic,
the limerick form’s quite elastic:
iamb, anapest, dactyl,
and trochee in fact’ll
mix well in a flow not too spastic.

(But that isn’t to say "no holds barred,"
for there _is_ a preferred form. Regard:
in lines 1, 2, and 5,
for 3 anapests strive,
3 & 4 get 2 feet, not "a yard."

And the rhyme scheme, moreover, is fixed
such that any divergence is nixed:
Thus "a-a-b-b-a"
it has been and shall stay
‘til all limerick rules be deep-sixed.)

Now it’s your turn, Dear Reader, so grab
Up your pen and for fun take a stab
At some lim'rick rhymes fittable
To this tune (it's hospitable)
And I’m sure the result will be fab.