It’s that look of “I think I just bit off more than I can chew.”
Which I totally identify, because I stretch to let people pull a hogtie tighter to show off how flexible I am. Or I let them make the bondage more difficult so I can feel tough.
And then when I’m settling into it, I’m stuck with that holy-crap-I-just-agreed-to-this feeling and I realize my bluffs have been met.