I've seen the "!" translated into English as "Ron't!".
The word "!" is a lispy way of saying "". (to cannot speak clearly / ).
It is used to joke around a little, and is used for hedonic or infantile expressions. It is slang for a subculture.
* * *
I'm not an expert, so I don't know, but some people have said the following.
> Ron't…/t, d, n, s, z//r/R-18
> Twitter / anima_solaris (via spindrift64)
> Ron'tDon't→Ron't(Ron't! : lowlevelaware)
> HENTAI