I just bought an electrostim unit. If you get the right setting it can feel really good. I also discovered the not so good feeling, which would be lots of fun to apply to someone else

I have a battery operated unit, which I had been using with the cock straps. I thought the battery was running down so I was turning the juice up. I stopped and put it down for a few minutes then came back. Now the first setting when you turn it on is burst mode. So I turned it on to discover that the battery had recovered and my 75% full setting hit me

Suffice to stay I winced a bit and appretiated somewhat how the girls on WiredPussy must feel or the guys on MenInPain. It might hurt a bit buts its a huge turn-on as well.