It isn’t necessary to use anal lube with a realistic butt toy because at the end of the day, it may look and feel real, but it isn’t actually a genuine butt. This means any sex lube will do, providing it is safe for use with the toy. Some silicone toys cannot be used with oil or silicone based lubes. If your toy is made from silicone then a water based lube will be best. Of course, you are fine to use an anal lube if you wish to as these lubes often have a thicker formula which some people prefer.