I don't quite understand the phrase and sentences in bold. Could anyone give me a hand?
Important aspects of the Sun's popular appeal identified by this group of interviewees evidently include its humour, 'street credible' sociability and simplifying common sense. As Pursehouse observes: "It gains credibility, almost becomes friends with readers, through appearing to 'talk the same language.'' The basis of this 'friendship', he argues, is on the grounds of 'a shared joke', although much of what counts as the Sun's 'fun persona' is gender-specific in that the tabloid typically position itself as 'one of the lads.'
'Street cred' is being respected by people on the street, not the media, etc. Madonna, for instance, has no street cred because she's a commercial product, while Djs, etc, often do because they are popular in those circles and don't get contracts to advertise products. When someone becomes successful and starts making lots of money, they are regarded as having 'sold out'.