\def\makeinnocent#1{\catcode`#1=12 }
\def\comment{\begingroup
  \let\do=\makeinnocent \dospecials
  \endlinechar`\^^M \catcode`\^^M=12 \xcomment}
{\catcode `\^^M=12 \endlinechar=-1 %
  \gdef\xcomment#1^^M{\def\test{#1}
  \ifx\test\endcomment \let\next=\endgroup
  \else \let\next=\xcomment \fi
  \next}
}
{\escapechar=-1
  \xdef\endcomment{\string\endcomment}}

\comment
Colaksdjf
{asdf{asdflkj
{AS{Dfasdf;lsdkjflkdf \proclaim abc.
\endcomment
Hello, world
\end