It could be a reference to the ASDF Videos... 184.108.40.206 12:31, 13 April 2014 (UTC)
- Eeeeeeeeeexcept that asdfmovie 2 (the one which includes the "it says gullible on the ceiling" sketch) was first uploaded in January 2010 ... a good 11 months after this comic was published. Given the style and timeline of the asdfmovie shorts, it's rather more likely that they were (as a whole!) inspired by xkcd, not the other way around... 220.127.116.11 15:45, 17 June 2014 (UTC)
Actually it's a really, really old practical joke. Note how cueball is clearly familiar with the gag and doesn't 'fall for it'. 18.104.22.168 15:30, 21 August 2014 (UTC)
- Actually, Blackhat actually says its an old joke.