\documentclass{beamer}
\usetheme{CambridgeUS}
\usepackage{listings}

\lstset{language=[LaTeX]TeX,
	morekeywords={draw,clip},
	keywordstyle=\color{blue},
	commentstyle=\color{red},
	frame=single}

\begin{document}

\begin{frame}[fragile]
\frametitle{Clip to a Rectangle}

A much simpler solution is to establish a clipping region.
\bigbreak

\begin{lstlisting}[escapeinside=!~]
\begin{tikzpicture}
\draw[help lines] (-5,-5) grid (5,5);
\draw[thick,<->] (-5,0) -- (5,0) node[right] {$x$};
\draw[thick,<->] (0,-5) -- (0,5) node[above] {$y$};
\begin{scope}
	\clip (-5,-5) rectangle (5,5);
	\draw [thick,blue] plot (\x,{\x*(\x+2)*(\x-2)}); 
\end{scope}
\end{tikzpicture}
\end{lstlisting}

\bigbreak

Compile \verb+workshop5.tex+ and note the difference. 

\end{frame}

\end{document}