One trick someone showed me:
Have the student put a pencil stub between the index and small finger resting on the back of the 2 middle fingers..if the student tenses up pain is caused.
Works even better with a cigarette if the student smokes! (in olden daze some did!) (They also drank, chased members of the opposite sex with the object of engaging in sex and wore watches of incredible size that cost more than their car!)