Obligatory Blow Job. The act of going down on one's male partner, either because he just went down on you and you owe him one, or because you don't want to bone him yet.
Sue: So, didja do him yet?
Jessica: Nah, I wasn't in the mood, but he was horny so I gave him an OBJ.
in the usenet forum rec.humor posters who wished to talk about off topic information were required to add an obligatory joke. They prefaced this with the acronym OBJ.
Stands for outstanding blow job. Given to a man because it was well deserved. Usually because he has done something spectacular. Also given until the recipient has achieved an orgasm. If bj's are given as part of foreplay, they usually aren't completed. Obj's are necessary every now and then.
Girlfriend: you are super sexual today!!! How about an Obj?!
Boyfriend: what about you?
Girlfriend: no, I'm fine. Giving you an obj would complete my life.
Loucy loves giving her boyfriend an obj on the reg.