Generally, this occurs if:
- The male has asked for a blowjob
- The male has allowed the female to spend time with him
- The male is horny
female: "But... I don't want to..."
male: "you don't have a choice; it's your blowjobligation."
female: "oh, you're right. ok."
Boy: Now it's time for you to fulfill your blowj-obligation! (begins to unzip jeans)