A nickname given to someone who uses the microwave oven of a different department on a different floor to warm up his/her lunch. The result is a witch hunt followed by deep hatred for that person for making the entire floor smell of fish.
Receptionist 1: What's that smell?
Receptionist 2: Hmmmm it smells like fish
Receptionist 1: Eurrghhhhhhh
Office worker 1: What is that smell?
Office worker 2: Someone is cooking something god awful in the microwave
Office worked 1: It must be someone cooking a fish pie.
Colleagues call the offending person fishpie from thereon in