Susan's son has a girlfriend.
She found this out when he posted it on FB. Susan's son is a boy of few words, so she took advantage of his online self disclosure and asked him some simple questions, all of which he answered.
The following day, Susan had a separate conversation with her social worker girlfriend and as a result has to have a substantive sex talk with her son.
Susan told her son that the sex talk was imminent and allowed him to choose which parent he'd prefer to have it with.
Susan's in the batter's box. She'll let you know how she does.