Following is a narration of events that turned the innocent shy housewife of my wife's sister into a slutty whore who gets regularly fucked by many men now, as a result of her voyeur hubby introducing her to adultery.
Her husband (my co-brother) who has an average cock had this voyeuristic desire to see his wife getting fucked by a cock bigger than his. Witnessing my cock led him to coax her to sleep with me. Losing her chastity by letting another man's cock penetrate her married cunt, yet getting better sexual satisfaction being fucked hard and fast by my 7+ tool, she lost her modesty and started sleeping with me regularly thereafter.
After fucking her many times and turning her to a cock crazy slut who was willing to try out other men, I introduced her to my friends too. Now she has turned into a real slut who gets fucked by many men for sometimes even for money. To heighten her cuckold voyeur hubby's desires, I sometime organize gang bangs for her so he could watch and masturbate while the guys take turns in fucking her heavily used holes. Because of her ability to satisfy the man she gets fucked by, she's in high demand.
To date, the number of times her married fuck-holes had been penetrated by other men's cocks is much greater than the times they were filled with her husband's during the whole 10 years of their marriage, and the difference is widening!
Enjoy my heavily used 'slutty sister-in-law'