When a musician uses their fame to express their uninvited opinions about politics, religion, and/or any other topic they feel like talking about. This is something Michael Stipe, of R.E.M., is famous for hence "stiped". This often occurs at a concert you paid money for to enjoy the music and not a self righteous speech.
Aw man, I went to see Pearl jam last night and was stiped by Eddie Vedder!