That the sister is interested in her foster brother's opinion is commendable. And assessing her worthiness from a man's point of view he can. But asking him to jerk off in front of her is kind of weird. He's going to get her, isn't he? Only this slutty girl is not scared at all - that's exactly what she wants. He ended up flushing a whole puddle on her tummy! Drove it.
If there's no work, then there's sex. That's how most girls get a job anyway. He fucked all the holes of the secretary, while she happily spread her legs and kneeled down.