Doesn’t happen all that often.
…but, really, I find it amazing that xkcd has never heard of Agatha’s Law:
I mean, the hero of this particular strip is a science-inclined type who’s just been able to personally observe dimensional travel. Directed dimensional travel, under the control of a human operator. He needs to get done with mourning the loss of his heroic fantasy adventure vacation and get started with reverse-engineering that shit.