When a guy fucks a woman without wearing a rubber (barebacking) so that when he unloads his semen (cum) into her pussy, she will become happy or happier; semen can also be unloaded down her throat to produce the happiness feeling
* Scientifically studied *
Lisa: (in a sad tone) I need your happy juice!
MOCO: Semen Therapy on the way!
Lisa: (after MOCO's explosion; in a happy tone) Thanks, I sure needed that!