% from https://en.wikibooks.org/wiki/LaTeX/Macros
\newcommand{\wbalTwo}[2][Wikimedia]{
This is the Wikibook about LaTeX
supported by {#1} and {#2}!}

\begin{itemize}
\item \wbalTwo{John Doe}
\item \wbalTwo[lots of users]{John Doe}
\end{itemize}