Green’s Dictionary of Slang

orifice n.

an office.

1971		L. Sanders Pleasures of Helen 149: ‘[You told me] when you departed for the orifice in the morning’.
1978		P. Theroux Picture Palace 249: Once, years before, he had been funny, speaking of going to the ‘orifice’ or the ‘uproar’.
2013		S. Kworrie Poetic Injustice 81: ‘Step into my orifice!’ my Manager did say / "We’re short of work, I've sacked the Clerk / I’m going to drop your pay".