Respuesta :

Insanity
The AABA format was song form of choice for Tin Pan Alley songwriters of American popular music. 

First, Second and Fourth verse are the same (A)
Third verse (The bridge) or (B) is different than the others.
Sort of like a Poem. Where the lines ryhme like AABA. The lines "a" all ryhme at the end but the line "b" does not unless there is another "b" line somewhere along the way.