Danny Phantom: Season 1, Episode 16
When Paulina witnesses Danny's ghost transformation, he fears the exposure. Imagine his surprise when Paulina swears to keep his secret - then becomes his girlfriend! Life is great for Danny, until he finds out that Paulina has actually been overshadowed by Johnny 13's girlfriend, Kitty, in her plot to make Johnny jealous. Danny reluctantly plays along to protect his own identity, but, when Kitty's welcome wears thin, Danny pleads with Johnny 13 to take her back. When Kitty abandons Paulina's body and goes back to her true love, Paulina resumes her indifference towards Danny Fenton - although she's now madly in love with Danny Phantom!