[MIT] A common rhetorical maneuver at MIT is to use any of the canonical random numbers as placeholders for variables. “The max function takes 42 arguments, for arbitrary values of 42.:” “There are 69 ways to leave your lover, for 69 = 50.” This is especially likely when the speaker has uttered a random number and realizes that it was not recognized as such, but even ‘non-random’ numbers are occasionally used in this fashion. A related joke is that π equals 3 — for small values of π and large values of 3.
Historical note: at MIT this usage has traditionally been traced to the programming language MAD (Michigan Algorithm Decoder), an Algol-58-like language that was the most common choice among mainstream (non-hacker) users at MIT in the mid-60s. It inherited from Algol-58 a control structure FOR VALUES OF X = 3, 7, 99 DO ... that would repeat the indicated instructions for each value in the list (unlike the usual FOR that only works for arithmetic sequences of values). MAD is long extinct, but similar for-constructs still flourish (e.g., in Unix's shell languages).