She Came In Through the Bathroom Window by The Beatles tells the story of a woman sneaking into a man's life, literally and metaphorically, through unconventional means. The key themes revolve around spontaneity, invasion of privacy, and unexpected romantic developments. A particularly poignant moment in the song is the playfulness and carefree attitude conveyed in the lyrics, reflecting the experimental vibe of the late 1960s when the song was created.