Tomorrow's Halloween episode of Up All Night features a guest turn from Will & Grace star Sean Hayes. In the episode, which is entitled "Ma'am'd," Ava (the irrepressible Maya Rudolph) and Walter (Hayes) team up create a Halloween haunted house the neighborhood has never seen. Ava's attempts to win over her unadoring neighbors backfires, though, when she and Hayes take the job one step too far. Think Saw — for children. Up All Night airs on NBC at 8:30 p.m. (or 9:30 p.m. Central).