I’ve covered that aspect already in other comment chains.
Also this picture is clearly a joke. You wouldn’t be able to actually use that to masturbate as the hole would grow rapidly. You’d have to lather your hands first using either bar or liquid soap.
Yeah jamming your dick into a solid bar of soap is gonna cause a lot of issues. The one I’d imagine being the first to worry about is your dick getting bruised cause bar soap ain’t exactly soft