This week’s episode of “Saturday Night Live” is clearly a repeat, because two of the show’s stars, Cecily Strong and Mike O’Brien, will be performing at Boston University on Saturday night. Sadly, the event is open to BU students only.Mark Shanahan can be reached at email@example.com. Follow him on Twitter @MarkAShanahan. Meredith Goldstein can be reached at firstname.lastname@example.org. Follow her on Twitter @MeredithGoldste.