Oh okay, I see what you mean. I think it's a normal oddity that all male sims have, but it's just more or less noticeable on certain body types.. With this body type that your sims have it's extremely noticeable.
Since you've got pictures, maybe try submitting a report on answers HQ. It doesn't seem anyone else has on this issue yet. I wouldn't expect it to get fixed because CAS issues like this rarely do, but it's worth a shot!