The times when your girlfriend is menstruating so you can't have sex or do anything sexual to her vagina. This means she might feel guilty for no pleasure for the boyfriend. This means your girlfriend goes down on you much more often than normal which results in more blow jobs for the boyfriend
BJ season comes around every 20 days or so in any relationship. The male looks forward to BJ season while the female does not due to bleeding of the vagina
Bill: Hey George, it looks like you going hunting! I guess Stacey is alone for the weekend?
George: Oh no, not at all. I will be with Stacey all weekend. I am staying home all and do not plan to leave bed
Bill: Then what are you hunting?
George: I am getting ready for tomorrow... Its BJ season!