WTFs by programming language repository on github
codeodor.com
codeodor.com
For Objective C, I have some light to shed on that situation. If you look at the search results for WTF and Objective C (through github's search), you'll see there are a lot of references to Webkit, which has the Web Template Framework, which gets abbreviated to WTF namespace in the code. ( I learned that from http://stackoverflow.com/questions/834179/wtf-is-wtf-in-webk... )
Like seeing how many people liberally apply 'that shit' to their comments and shit: https://github.com/search?type=Everything&language=&...
Edit: Also takes no account for the quantity of code in each repository. Languages that are used for large projects are at an automatic disadvantage.
I think it would be cool if they made some aggregate data like that available though. =)
CSS is also surprisingly low. I would have expected it to dwarf any actual programming language, because IE6 exists, but it's actually lower than most. (Joeboy has a possible explanation: http://news.ycombinator.com/item?id=2899418)
I also find it interesting that functional languages (Haskell, Erlang) are pretty low. These have been thrust into a more mainstream light lately, so I'd imagine they'd be doing worse from programmers who are less experienced in them using them. But they're not like that at all. If anything, Haskell has done pretty good.
That said, I do know that WoW UI mods are written in Lua, and I also know that there's an interface-related folder in the WoW directory structure called WTF. If there are a lot of WoW mods on github, this could be related to Lua's outlier WTF status.