%:include <stdio.h>
%:include <Cocoa/Cocoa.h>
int main()
<%
NSString *message = @"Hello, world";
printf("%s\n", <:message UTF8String:>);
return 0;
%>
It's section 6.4.6 in the C spec. Good stuff for playing jokes on coworkers, but please don't ship code like this.