vag gadgada dravate yasya cittam
rudaty abhiksnam hasati kvacic ca
vilajja udgayati nrtyate ca
mad-bhakti-yukto bhuvanam punati
A devotee whose speech is sometimes choked up, whose heart melts, who cries continually and sometimes laughs, who feels ashamed and cries out loudly and then dances — a devotee thus fixed in loving service to Me purifies the entire universe.
Vag gadgada refers to a highly emotional state in which the throat is choked up and one cannot express oneself. Vilajjah indicates that a devotee sometimes feels embarrassment due to bodily functions and memories of past sinful activities. In this condition, a devotee loudly cries out the holy name of Krsna and sometimes dances in ecstasy. As stated here, such a devotee purifies the three worlds.
By melting of the heart, one becomes very steady in spiritual life. Normally, one whose heart easily melts is thought to be unsteady; but because Lord Krsna is the stable foundation of all existence, one whose heart melts in love of Krsna becomes most stable and cannot be disturbed by opposing arguments, bodily suffering, mental problems, supernatural disasters or the interference of envious persons. Because such a devotee is fixed in loving service to the Lord, he becomes the very heart of the Personality of Godhead.