The director of "Ingrid Goes West" makes an unexpected return to features with this sweet and silly comedy about long-lost "brothers." As far as I know, Netflix’s slight but undeniably funny “ Little Brother ” is the first streaming movie in which Michelle Monaghan is caught tonguing John Cena’s butthole on the side of a public road in suburban New Jersey (their characters’ teenage sons happen to drive by at just the wrong time), but at this point I’d probably have to believe you if you told me