Possible Clues:

• Refrain syllables
• “Hey Jude” snippet
• Bit of “Hey Jude”
• "Hey Jude" syllables
• Chorus syllables
• Repeating part of 'Hey Jude'
• Part of the "Hey Jude" refrain
• Refrain bit
• Lyric substitution, perhaps
• 'Hey Jude' sounds