Having sex 3-4 times a week was associated with a significantly greater stone passage rate than tamsulosin or standard medical therapy.
Source: Sexual Intercourse May Clear Distal Ureteral Stones
This was an interesting study that compared men that had stones that they were trying to pass. Some of the men were treated with flomax, which is commonly prescribed to help pass stones by allowing the ureter (kidney drainage tube) to relax and allow the stone more room to pass. Other men were not given anything and some of the men had regular sexual intercourse.
The men that had regular sexual relations had the highest rate of passing stones.
I will start advising my patients to increase sexual activity when trying to pass stones based on this study.