\documentclass{book}
\usepackage{xcolor,graphicx}
\usepackage{afterpage}

\newcommand{\noticecallout}[2]{
    \fcolorbox{black}{violet!20}{
    \begin{minipage}{10cm}
        \includegraphics[width=4mm,height=4mm]{danger.png}
        {\bf #1!}

        #2
    \end{minipage}
    }
}

\begin{document}
    \noticecallout{Never pour boiling water on plants}{Its not great for them.}

    \noticecallout{Dogs cannot survive great falls}{
        You are thinking of cats. Please do not throw Rex off the roof, or he may never woof again.
    }
\end{document}