The “hay is for horses” call back is from a cockney poem based on the alphabet but not the traditional “A is for Apple”. My dad, who was from London, England used to recite it to me whenever I said “hey” or “eh” (yes, I am Canadian).
My memory recalls the poem as follows:
Hay is for horses (A)
Beef or mutton
Seaforth Islanders (C)
Differential
Heave a brick (E)
Effervescent (F)
… I think G for a Q (Guinea for a ? )
I will do a search later to find the rest.