There is nothing untoward happening here; Lynne has merely commented that it is Belinda's birthday today. Maybe because she saw Belinda outside the gym, or maybe she was wondering why they all aren't going for a lunch or something. It's 'Mantha's comment which is puzzling. These women are probably in there late 20s or early 30s, have husbands and live in a suburban town. Why on earth would they be giving a friend the bumps? 'Mantha asks this question so matter of factly that she expects someone will give Belinda the bumps. No 'Mantha, no one is giving Belinda the bumps.
Lynne brushes off this nonsense by saying that she has only been bumped since her boob job. This boob job must have happened recently as we then see the well endowed Belinda showing off her large breasts. Lynne's comment implies that, and this is if being bumped is a double entendre for having sex, Belinda has only had sex since her boob job. What was wrong with her before? We can only assume that she had serious self confidence issues from having strangely shaped breasts, so much so that it stopped her having any physical relationship with any man. Now, however, since her recent surgical enhancement she has been getting her end away left right and centre with any man who makes a shocked face at her.
Bravo to you Belinda for gaining your confidence, but please don't turn into the town slut, and if you're going to sleep with any of those men, make it the man in the black suit as the man in the blue suit is walking away and the man in the brown suit has all the wrong body language.