[dsp1234]

> language injection where you write code and later on you inject a different language.

I (still) work with a Classic ASP code base.

I kid you not, that there are VBScript functions, which call JScript (not JavaScript) functions, which in turn call VBScript functions.

It is a terrifying and glorious mess.

edit:

I also worked with a system at one time that used node.js to create C# files on the file system, then use the C# compiler to create an executable and then run it. It was... not great.

[maxxxxx]

The funny thing is that these things may still have been the best solution for the problem within the available time. I have created some things that in hindsight were horrific but at the time they were the best that could be done.