 Some "tail" butt plugs popular in human puppy play are molded from medical grade silicone allowing a simulated tail "wag".Sex toys that are used in the anus can easily get lost as rectal muscles contract and can suck an object up and up, potentially obstructing the colon; to prevent this from occurring, it is recommended that individuals use sex toys with a flared base or a string.However, the flared flange is not a foolproof method of preventing the plug from entering the rectum completely with the inability to retrieve it.