All characters are 18+ in this story.
She was playing a more dangerous game now. She had been watching Dad masturbate from the safety of the upstairs bedroom for a long time and never had she done anything unmistakably suspicious, but yesterday she had lost touch with reality when she'd sneaked there to lap up the ejaculate from the magazine which had collected it. She had been greedy and consumed too much and if her father had had the idea to check, the resulting absence would have been hard to pin on evaporation alone. Much worse, she had panicked in fear of being thus confounded and acted foolishly and closed the magazine so that perhaps Dad would put it away without real care like last time. She would not be so careless next time, for there would undoubtfully be a next time, and would perfect the art of drinking and eating her father's expense in the sneakiest of fashion so that this could carry-on forever; or so she construed for her teenage mind was quick to extend the fortunate sleight of fate into infinity.
She did in fact repeat the experiment and stayed good to her promise of moderation for quite some time, contenting herself of witnessing Dad's ejaculation when he did it in a fashion which made the result too much of a risk to reach. But she could not help but find her own act of masturbation a whole lot more pleasurable when it was done with the taste of Dad's sperm in her mouth, for she reckoned there was something parietal in the experience which gave it an otherworldly feel and made for unsufferable comparison to it's absence. The thought to look for another man's semen did not however strike her mind and this could have been of some concern to her if it had been put to her in plain terms but she found the experience too enjoyable to question and so she never did. At no point either did she abandon the doggy position to masturbate for when she did use the hole to look down to her father's stimulation it was a necessity and when she came back from his room with her other fetish satisfied she returned to it naturally.