She's gonna tear your heart apart
No no way will she deceive [or]
No no, Ne'er will she deceive

The story:

For forty years I resolutely refused to believe that such a daft word as "nay" could possibly be the correct lyric, so I sang it one way or the other and instructed others that my way was correct. I finally became convinced by the overwhelming testimony of songbooks and Beatles websites that "nay" is in fact the correct lyric.