Pain tolerance

I was reading some whump and I finally realised what it is exactly that gives me instant whumperflies, every time:

Another character commenting on the whumpee's pain tolerance, usually in their internal monologue or even out loud.

Like, maybe the caretaker gets a glimpse of some poorly covered up injury and all they can think is 'how high must their pain tolerance be to walk around all day as if it were nothing?'

Or maybe, a character is forced to watch another be hurt and they can't tell if they're impressed or slightly horrified by how well the whumpee takes the torture, staying still and quiet, because 'what must have happened to them for them to take the pain like that?'

Or maybe, it's the whumper saying it, mocking the whumpee in a sickly sweet voice, dripping with fake care, because 'oh you're so well behaved, so good at taking everything I do to you. One would almost think you enjoy it,' and the whumpee feels sick at the words, because what if they're true?