Nnews about the President’s grandmother living in a remote Kenyan village prompt several amateur crooks to plot a kidnapping and demand ransom from the White House for the release of “Obamama,” as the French kidnappers call her. Their plans are thwarted less by the lax local security than by their own ineptitude. The various kidnappers get in each other’s way, only to end up, more or less, empty-handed.