"Dr. Seuss's Passover" joke

Why is it only
on Passover night
we never know how
to do anything right?
We don't eat our meals
in the regular ways,
the ways that we do
on all other days.
'Cause on all other nights
we may eat
all kinds of wonderful
good bready treats,
like big purple pizza
that tastes like a pickle,
crumbly crackers
and pink pumpernickel,
sassafras sandwich
and tiger on rye,
fifty falafels in pita,
fresh-fried,
with peanut-butter
and tangerine sauce
spread onto each side
up-and-down, then across,
and toasted whole-wheat bread
with liver and ducks,
and crumpets and dumplings,
and bagels and lox,
and doughnuts with one hole
and doughnuts with four,
and cake with six layers
and windows and doors.
Yes-
on all other nights
we eat all kinds of bread,
but tonight of all nights
we munch matzah instead.
And on all other nights
we devour
vegetables, green things,
and bushes and flowers,
lettuce that's leafy
and candy-striped spinach,
fresh silly celery
(Have more when you're finished!)
cabbage that's flown
from the jungles of Glome
by a polka-dot bird
who can't find his way home,
daisies and roses
and inside-out grass
and artichoke hearts
that are simply first class!
Sixty asparagus tips
served in glasses
with anchovy sauce
and some sticky molasses-
But on Passover night
you would never consider
eating an herb
that wasn't all bitter.
And on all other nights
you would probably flip
if anyone asked you
how often you dip.
On some days I only dip
one Bup-Bup egg
in a teaspoon of vinegar
mixed with nutmeg,
but sometimes we take
more than ten thousand tails
of the Yakkity-birds
that are hunted in Wales,
and dip them in vats
full of Mumbegum juice.
Then we feed them to Harold,
our six-legged moose.
Or we don't dip at all!
We don't ask your advice.
So why on this night
do we have to dip twice?
And on all other nights
we can sit as we please,
on our heads, on our elbows,
our backs or our knees,
or hang by our toes
from the tail of a Glump,
or on top of a camel
with one or two humps,
with our foot on the table,
our nose on the floor,
with one ear in the window
and one out the door, doing somersaults
over the greasy k'nishes
or dancing a jig
without breaking the dishes.
Yes-
on all other nights
you sit nicely when dining-
So why on this night
must it all be reclining?