Funuckered

Meaning absolutely dead on your feet. More than tired, more than exhausted and more than knackered/shattered. Another way of saying (f*cking knackered)

I am absolutely Funuckered today. My body won't function.

Giffer

An old person. Usually an old man. Usually UK slang, can be used against the younger generation.

"You coming out drinking tonight Matt?"

"No, I'm tired from work. Gonna take a nap and chill"

"Don't be such an old Giffer, come out drinking"