“Har har Mahadev” is a slogan honouring Shiva that helps recognising and uniting Banarasis.
(Malik can be literally translated as ‘owner’, but in Banarasi sense, it is something comparable to ‘sir’. A typical Banarasi term of address.)
(Ka Guru can be translated as ‘hello guru’. Another typical Banarasi term of address.)
(Mast = delighted/fun/well/fine)