Shining a torch in the dark

You can carry out a simple experiment to see if threadworms affect members of your household. Several hours after bedtime go into the bedroom (do not turn on the light) and shine a torch on the anus. You will easily be able to see the worms because the light makes the worms move back into the anus.

stick a torch in someone's ass?

Nani? i thought the threadworms entered the anus and exited the fingers...