CC Antya 15.75

sulalita dīrghārgala, kṛṣṇera bhuja-yugala,
bhuja nahe, — kṛṣṇa-sarpa-kāya
dui śaila-chidre paiśe, nārīra hṛdaye daṁśe,
mare nārī se viṣa-jvālāya
Word for word: 
su-lalita — very beautiful; dīrgha-argala — long bolts; kṛṣṇera — of Kṛṣṇa; bhuja-yugala — two arms; bhuja — arms; nahe — not; kṛṣṇa — black; sarpa — of snakes; kāya — bodies; dui — two; śaila-chidre — in the space between the hills; paiśe — enter; nārīra — of women; hṛdaye — the hearts; daṁśe — bite; mare — die; nārī — women; se — that; viṣa-jvālāya — from the burning of the poison.
Translation: 
“The two very beautiful arms of Kṛṣṇa are just like long bolts. They also resemble the bodies of black snakes that enter the space between the two hill-like breasts of women and bite their hearts. The women then die from the burning poison.
Purport: 

In other words, the gopīs become very much agitated by lusty desire; they are burning due to the poisonous bite inflicted by the black snakes of Kṛṣṇa’s beautiful arms.