Jaadu ki Jhappi was a phrase introduced in Hindi film Munna Bhai MBBS. Jaadu here means magic, and jhappi, which is not a standard Hindi word, is used for a hug.
The phrase means a hug, which the hero of the film used to give to anyone in trouble, to make them feel better. He believed it was a magic cure for stress and made people feel better instantly, and so he called it a magical hug, Jaadoo ki Jhappi.
Jaadu ki Jhappi is also an item song featuring Jacqueline Fernandez in Hindi film Ramaiya Vastavaiya.