The father trains his son to last as long as possible before cumming, so when he will fuck a pussy for the first time he won't make a bad impression. This training is probably done every day. The son must try as hard as possible to hold back the cum, otherwise he will be punished.
to Blueweaver12 :I have been trained that way - daily slow masturbations - punishment for coming without permission- I am also being trained to TAKE cock not to fuck pussy.
to Blueweaver12 :he enjoys edging me and often denies ejac. I am punished when I do ejac almost always . I am now in chastity and get fucked three or more times a day