Connect all the individual pics! :D
Clue would be that there's 'some' pictures missing; tie it to Friday the 13th.

Sigh...since no one's got the funda as yet, here's the answer; clockwise from left - Matsyasana(The Fish), Koormasana(The Tortoise), Simhasana(The Lion), Dhanurasana(The Bow), Chakrasana(The Wheel), Vatayanasana(The Horse), Halasana(The Plough) - representing Matsya, Koorma, Narasimha, Rama, Krishna, Kalki and Balarama respectively; the ones missing being Varaaha, Vaamana and Parashurama. The connect being obvious; the ten avatars of Vishnu; the funda with Friday the 13th; oh well...you know which movie hits the theatres today!

Excuse the arbitness! :)