Armpits.

So Ebedmelech took the men with him, and went into the house of the king under the treasury, and took thence old cast clouts and old rotten rags, and let them down by cords into the dungeon to Jeremiah. And Ebedmelech the Ethiopian said unto Jeremiah, Put now these old cast clouts and rotten rags under thine ARMHOLES under the cords. And Jeremiah did so. So they drew up Jeremiah with cords, and took him up out of the dungeon: and Jeremiah remained in the court of the prison. ( Jeremiah 38:11-13 )