your friend can file police complaint against the man under section 509 of IPC for outraging the modesty of your friend
2)Section 509 talks about words, gestures or act intended to insult the modesty of a woman.
3)the essential elements of the section are:
Accused uttered any word, made any sound or made a gesture or exhibits any object or intrude the privacy.
Accused intended that words uttered, sound made or gesture shown or object exhibited seen or heard by the woman.
It has to be directed towards a woman or group of women
4)“shall be punished with simple imprisonment for a term which may extend to three years and shall also be liable to fine”