
The text plays random snippets of abc_123_a.ogg every time a character is typed out. A glitchy, robotic sound named mus_smile plays in the background, and when sped up is revealed to be Muffet's laugh reversed then played twice. Room 264, otherwise known as room_gaster, is black and displays shaking, white text in a pixelated Wingdings font.

The one behind you, with the creepy smile.

The room has a thin stretch of land surrounded by water on two sides. Its name suggests that Toby Fox may have planned to place it before the small bird that carries the protagonist over a disproportionately small gap. Room 123, also known as room_water_prebird, is between room_water_farm and room_water_shop. The rooms below are listed in numerical order. If the player attempts to access these inaccessible rooms (the "Dogcheck" rooms are 0–3, 78–80, 239–241, and 266–335), the "Dogcheck" value returns out of range and cause the Annoying Dog to appear in the middle of a black screen while " Sigh of Dog" or " Dance of Dog" plays.

In Undertale's game files, the player cannot access some rooms by conventional means.
