Phineas and Ferb Season 3 Episode 44
The Mom Attractor
When the boys ask Candace to decide what they should do for the day, she slyly asks them to invent a device to attract their Mom so that she can finally bust her brothers. Meanwhile, Dr. Doofenshmirtz has invented a "Baby-Cry-Inator" designed to tarnish his goodie-two-shoes brother's image with the electorate.