She fastened it with the pin, and said to him, The Philistines are on you, Samson. He awakened out of his sleep, and plucked away the pin of the beam, and the web.
The fact that Samson told Delilah to do something to his hair (Judges 16:13) suggests that he was giving her a clue to his strength. She did not pick this up but kept hounding him for his secret. Finally he gave in (Judges 16:17; cf. Judges 14:17).