Hello spark. I have had subs orgasm strictly due to the sensation of the sound - with no other stimulation except the sliding of the sound. Those people report that is feels like being fucked from the inside. This reaction is not the norm, however.

Most people say it just feels odd or slightly uncomfortable. Usually there is a bit of a sting as the sounds passes the opening - there are a ton of nerves right there. Once in, you are usually ok unless you have scar tissue inside. If you passed kidney stones you may want to pass on sounding.