With a single finger still tickling the head of his cock, begin to move your other hand up and down his shaft with a light grip. By this time, he should be so excited that precum is leaking out of the tip of his penis. If it isn’t there already, see if you can use this combined stimulation to bring out a drop or two.
Say: “I know what happens to a man when his dick is teased by a woman who really knows what she’s doing. His poor straining penis start to cry. Little tears of pre-cum start to flow from the tip of his cockhead. Look! It’s happening to you too!”