"Surprise", as I understand it, is something rational agents experience when an observation disconfirms the hypothesis they currently believe in relative to the hypothesis that "something is going on", or the set of unknown unknowns.

If you generate ten numbers 1-10 from a process you think is random, and it comes up 5285590861, that is no reason to be surprised, because the sequence is algorithmically complex, and the hypothesis that "something is going on" assigns it a conditional probability no higher than the hypothesis that the process is random. But if it comes up 1212121212, that is reason to be surprised, because the sequence is algorithmically simple, so the hypothesis that "something is going on" assigns it higher conditional probability than the hypothesis that the process is random. The surprised agent is then justified in sitting up and expending resources trying to gather more info.