When the antagonist/torturer asks the defiant whumpee a casual rhetorical question about themself that suggests they're about to really fuck them up.
“It was the left leg last time, right?” - The Flash
“But a man cares about his son, eh?” - Percy Jackson
“I believe you know…[produces photograph]…this person?”
“You write with your left hand, don’t you, [name]?” - one of my own
And either the whumpee is confused and has no idea why they’ve suddenly changed the subject or they realise immediately what they intend and get an ice-cold jolt of fear right through their veins.