The song 'What's That You're Doing?' by Paul McCartney is a playful and energetic track that showcases a blend of pop and funk influences. The lyrics revolve around the themes of curiosity and fascination with a partner's actions and behavior. McCartney expresses a sense of intrigue and wonder, asking repeatedly about what the other person is doing and how it captivates him. Key themes include fascination, curiosity, and the playful nature of relationships. Poignant moments in the song include the repeated questioning, which emphasizes the wonder and enchantment McCartney feels about his partner's actions. Overall, the song is a lighthearted take on the joy and excitement that comes from being captivated by someone you care about.