L     said, “A Lamp pray keep alight, to make some barley tea.”
M     said, “A Mulberry or two might give him satisfaction.”
N     said, “Some Nuts, if rolled about, might be a slight attraction.”
O     said, “An Owl might make him laugh, if only it would wink.”
P     said, “Some Poetry might be read aloud, to make him think.”
Q     said, “A Quince I recommend,—A Quince, or else a Quail.”
R     said, “Some Rats might make him move, if fastened by their tail.”
S     said, “A Song should now be sung, in hopes to make him laugh!”
T     said, “A Turnip might avail, if sliced or cut in half.”
U     said, “An Urn, with water hot, place underneath his chin!”
V     said, “I'll stand upon a chair, and play a Violin!”
W     said, “Some Whiskey-Whizzgigs fetch, some marbles and a ball!”
X     said, “Some double XX ale would be the best of all!”
Y     said, “Some Yeast mised up with salt would make a perfect plaster!”
Z     said, “Here is a box of Zinc! Get in my little master!
We'll shut you up! We'll nail you down!
Likely a reference to the old-fashioned practice of  designating beer X, XX, or XXX according to its alcohol content. 
 Nothing to do with  Dos Equis beer,  first brewed in 1897, 9 years after Lear’s death. (The name was a reference to the coming twentieth–XX–century.)
Alphabet Poem A tumbled down...