A collection of porn
in any form. As you would say a "flock" of sheep you say a "kettle" of porn. However kettle can be used on its own with the same effect.
Farmer Jess: I have a chicken kettle at home, would you like some?
Dr Jamie: No, i prefer male kettles to be honest.
(this shows Farmer Jess is very into animal sex and Jamie is homosexual :D)