Jawaharlal Nehru University Students' Union (JNUSU) president Kanhaiya Kumar was today shown black flags at a function in Patna by two persons who were roughed up by his supporters before being detained by the police for questioning. The two persons belonging to a little-known outfit -'Youth Swaraj' - showed black flags to the JNUSU president, besides raising slogan of 'Bharat Mata Ki Jai' while he was speaking at a function 'Azadi' in SK Memorial hall in Patna organised by AISF and AIYF. Mr Kumar's supporters thrashed the two persons in the hall. Later the police took the duo into custody.