Funny side story - when I was working as a volunteer in the PAWS Wildlife Rescue center here in Lynnwood, WA, I had the task of scrubbing native turtles who were experiencing severe shell rot. Veterinarians couldn't figure out why this was happening and so the turtles in our care - some very large actually for a local turtle - got shell scrubbings with antibacterial soap and a solution applied afterward. Not sure what that was. The vet made it up.
Well there was this one turtle - the largest one - I called him Bob (no idea why) but he LIKED to have his shell scrubbed and, in fact, would extend his male member so that the unknowing would FREAK OUT. It happened a lot. You see that turtle weenie coming out like a snake and it's a bit crazy..........