Long time ago, some really strange characters encodings were used.
For example, a character encoding for the German language DIN 66003 was in use from 1974 to 1999. It was created by modifying the ASCII encoding, namely replacing characters [\]{|}~ with ÄÖÜäöüß. It was a cool idea as for those days - look, some unecessary brackets were replaced with actual letters of the alphabet!
In order to make it possible to write C++ code on such encodings, there was an ingenious approach - one can write <%, %>, <:, :>, %:, %:%: instead of {, }, [, ], #.
Combining with legal substitutions && -> and, != -> not_eq, etc., this code will compile:
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int main(int argc, char* argv<::>)
<%
// lambda with reference-capture:
auto greet = <:bitand:>(const char* name)
<%
std::cout << "Hello " << name
<< " from " << argv<:0:> << '\n';
%>;
if (argc > 1 and argv<:1:> not_eq nullptr) <%
greet(argv<:1:>);
%> else <%
greet("Anon");
%>
%>
To add more fun, C/C++ has “trigraphs” - one can substitute { -> ??<, [ -> ??(, and so on.