Mrs. BMB has done this a number of times.

Frequently when I manually stimulate her, she will gently squeeze my balls. After a manual orgasm, she is particularly sensitive and particularly horney. She wants the big shaft. Sometimes I can get away with giving her another manual orgasm. But more frequently, if I am slow bringing the shaft to her she will very forcefully grab my balls and put me where she wants me. If I am the least bit flaccid, then she really abuses the boys with vicious squeezing. It's times like that when I wish I had a gag for silence. The pain is both excruciating and delicious.

Once fully pumped again, often she'll then go doggy style, claiming that she feels it more, further "up" inside. If we go on for a while, when she begins to get tired, she will reach under, grab my boys, and as described below, nearly pull them off until we both orgasm and collapse.

Quote Originally Posted by tlgibson54 View Post
Over time I have persuaded my SO to give my balls a firm massage before intercourse, to ah, stimulate release. Unfortunately, she has a terrible phobia that she will damage me permanently, so we have never gone nearly far enough as far as I am concerned. Although I have never told her, when she is particularly eager for penetration from doggy style, she will reach between her legs, grab my balls and almost pull them off their stalks!