hey guys. I'm trying to find a specific tag along the lines of hidden/secret/inconspicuous masturbation, like somebody secretly masturbating or trying to hide the fact that they're masturbating (kind of like the painter in post #1676873 but as if he were trying to hide that he's masturbating by being behind the painting). I've tried combinations of those words but cannot seem to find the proper tag. is there a tag that's like this?

Stealth masturbation is the tag you're looking for.

Also relevant: under_table, hidden_vibrator, and sex_toy_under_clothing
You could search:
under_table masturbation
~hidden_vibrator ~sex_toy_under_clothing