I am friends with a married couple where the wife confides in me with relationship issues and happenings. Recently, the wife informed me that she has only been using sex as a "behavioral training mechanism" (her words) to get her husband to complete various domestic tasks. For instance, she has rewarded emptying the dishwasher with daily sex as reinforcement. After three weeks, the dishwasher has continued to be emptied sans sex. This has apparently occurred on multiple occasions for cleaning and other household tasks.