What the hell did that lecherous daughter slip into her father's tea, some kind of stimulant? She deliberately wanted him to get a hard-on, and she walked around the house in her panties! And where could the man go when his head had already caught the target. No dick could resist that temptation.
Well if you don't have anybody to have sex with, you can have fun with your sister in the 69 position, and they're pretty good at it.