f.i. or f.o.
Fit in or fuck off is when your boss tells you to shut up and do what they say or else you’re out. No talk. No debate.
My boss said, 'Fit in or fuck off, or I’ll make your life a nightmare.'
The new employee was told, 'Fit in or fuck off, or I’ll make you my enemy.'
At the meeting, the boss said, 'Fit in or fuck off, or I’ll fire you on the spot.'