Searching story about guy flirting with aunt and then stumbling across mom aunt dad uncle foursome

[ssamforfun]

Hi, long ago I had read a story where a teenager is forced to go to ancestral home along with parents, where he end up flirting with aunt. Later in the night, he peeps into aunts room to find her enjoying a foursome with mom aunt and dad. Was a great read and now I am trying to find that story again. However, despite multiple searches I am unable to find the story. Can someone help me with this? Thanks.