A fair share of the WTFs for python are probably due to the WTForms library. I count 6 out of 10 WTForms matches on the first page of github file results.
Is the graph normalized to account for lines of code per repository? WTFs by repository is a useless number: I'd be more interested in seeing the WTFs per line.
Last year I did something similar, but instead of searching the code I looked at commit messages that matched certain patterns to categorize them by emotions, you can see the results here
People would probably only use wtf if the language did something that they didn't expect of it, regardless of how wtf the language actually is. This just shows that Python programmers programming in Python use WTF x times and Java programmers using Java use WTF y times.
(This would also explain why the wtf rate for Javascript is so low ;) )
The answer is in the comments of that site. Lua is used in lots of places, but the earliest "famous" one is World of Warcraft, where it is used to make extensions. The folder where those extensions are stored is called WTF (Warcraft Text File), so on every warcraft extension the string WTF appears multiple times. See http://www.wowwiki.com/WTF
[+] [-] sigil|12 years ago|reply
https://github.com/search?q=wtf+extension%3Apy&type=Code&ref...
[+] [-] manojlds|12 years ago|reply
[+] [-] grannyg00se|12 years ago|reply
[+] [-] eksith|12 years ago|reply
[+] [-] jfasi|12 years ago|reply
[+] [-] Nav_Panel|12 years ago|reply
Perhaps something like WTFs per commit would be best?
[+] [-] unknown|12 years ago|reply
[deleted]
[+] [-] yaph|12 years ago|reply
http://geeksta.net/geeklog/exploring-expressions-emotions-gi...
[+] [-] rheide|12 years ago|reply
(This would also explain why the wtf rate for Javascript is so low ;) )
[+] [-] pintglass|12 years ago|reply
https://github.com/search?q=wtf+extension%3Alua&type=Code&re...
[+] [-] otikik|12 years ago|reply
[+] [-] colanderman|12 years ago|reply
[+] [-] contingencies|12 years ago|reply
[+] [-] ams6110|12 years ago|reply
[+] [-] atmosx|12 years ago|reply
[+] [-] SameGamchee|12 years ago|reply
[+] [-] platypii|12 years ago|reply
"What a Terrible Failure: Report an exception that should never happen."
http://developer.android.com/reference/android/util/Log.html..., java.lang.String)
[+] [-] ianstallings|12 years ago|reply
[+] [-] shazeline|12 years ago|reply
http://www.youtube.com/watch?v=V44kscaJe3M