On the left side of John's shirt it looks like a line of dried up semen, and it looks like there's also a small trace of semen on the right side of of the other guys shirt.
I think this all makes sense. The story here is obvious:
They had a three some (the traces of semen proves that, not to mention that both of the males in the pic are hard). John's wife's left hand looks the way it does (veins popping out and all) because she jacked both of them off and you can tell they had a three some cause they all have smiles on their faces to go along with the rest of obvious signs, not to mention John's wifes breasts looking a little more firm then a womens breasts normally should look..
The two gross things in this picture: Both males have small traces of semen on their shirts (or what looks like semen).