If you can get a co-worker to help...
If you have access to the filing cabinets...
You could take a picture of you on your knees in a submissive pose... even (innocently) crossing your hands and resting them on a half open drawer.

Open submission, hidden in plain sight in the vanilla world.

If the co-worker is female... maybe even a hint of leg if you're skirted.
Hell, you might even show more than a hint if you are "conspiratorial" with your co-worker and tell her you want to surprise your boyfriend.