A panty fashion show is the first domino in a chain reaction leading to incest.

The guy was calmly sitting at his computer looking for porn with his stepmother when his stepmother called him into her room and... asked him to help her choose panties that would best seduce his father into having sex with her. An unexpected turn of events, but it was the first domino in a whole chain that set off a chain reaction. The stepmother changed her panties, the stepson's cock got hard... a blowjob, sex with his sleeping stepmother on the couch, and off they went.