What is the #frozenchook? Is it performance art? An anti-meat demonstration? Some kind of sex thing?

Nah, man. You're thinking too hard.

#Frozenchook just a thing you can do while your next to a thing or on top of a thing. Or not. But you have to be naked. And positioned like a frozen chicken. Or a "chook," because it's a New Zealand thing, and that's what they call chicken there. Or something. 

Just go with it...