\documentclass{article}
\begin{document}

\hbox{t $m$ t}

\hbox{t $$t$$ t}

Footnote\footnote{t $m$ t}
Another\footnote{t $$m$$ t}

\begin{minipage}{3in}
t $$m$$ t
\end{minipage}

\hbox{\begin{minipage}{3in}
t $$m$$ t
\end{minipage}}

\parbox{3in}{t $$m$$ t}

\hbox{\parbox{3in}{t $$m$$ t}}

Note that dollar inside equation, etc.~fails.
% \[ m {\rm $t$ } m \]

% \[ m $$m$$ m \]

\mbox{t $m$ t}

\mbox{t $$t$$ t}

\[ a + \mbox{t $m$ t}  + c \]

\[ a + \mbox{t $$t$$ t}  + c \]

\[ a + \makebox{t $m$ t}  + c \]

\[ a + \makebox{t $$t$$ t}  + c \]

Base\raisebox{1em}{t $m$ t}

Base\raisebox{1em}{t $$t$$ t}

Base\shortstack{t\\ $m$\\ t}

Base\shortstack{t\\$$t$$\\ t}


\end{document}