Üvey oğlumun mastürbasyon yaptığını fark ettim ve onun devasa penisine binmeye karar verdim

I passed through his half-open door, I saw him on the bed, hands moving. I should have left, but he saw me, he didn't stop, he invited me with his eyes. I went in, undressed, climbed on top of it. I ended up with him inside, both smiling, promising to leave the door open more often.