You don’t see bands rocking letterman jackets on late night television very often, so thankfully Girls bucked that non-trend last night on Conan, where they stopped by to perform “Love Like a River,” the next-to-last cut from their excellent 2011 album, Father, Son, Holy Ghost. Along with high school fashion cues, the band brought their flower-heavy set design and gorgeous-sounding back-up singers that balanced out singer Chris Owens’ forlorn crooning.