Tequila Mockingbird reminded me of some other non-lyrical Mondegreens. My mother, when teaching Composition at ECU, had a student turn in a paper referring to an author winning the Pullet Surprise. She also got a paper that she was expecting to be about euthanasia which was instead about youth in asia. My personal favorite, though, is the student who, intending to write "Voila!" instead wrote "Viola!" (That's a standard phrase in my house now.)
On the lyrical side, I (as a small child) sang the words to the Grateful Dead song "Casey Jones" as "Ridin' that train, Hi, I'm ok!"