Title text: The universe started in 1970. Anyone claiming to be over 38 is lying about their age.
In computer systems, time is measured starting from some arbitrarily chosen point. That particular time is known as the "epoch" for that system. The UNIX operating system internally uses an epoch of January 1, 1970, and measures the time as a number of seconds from then. Since this was intended only for things internal to the OS (File last modified times and the like), using 1-Jan-1970 was safe as no UNIX systems existed before that date.
Dates before January 01, 1970 are represented by negative values. At 03:14:08 on January 19, 2038 the 32-bit versions of the Unix time stamp will cease to work, as it will overflow the largest value that can be held in a signed 32-bit number. The 64-bit version will expire at 15:30:08 December 4, 292,277,026,596.
Cueball has clearly misused the system date in some way, his friend makes a pun by combining "Epoch" with "Epic Fail" - a colloquial term meaning "a very big mistake was made".
The title text takes the joke to the next level, claiming that the entire universe began when Unix did, and therefore no one can be older than 38 (at the time of the comic), which would explain away the bug since no later dates would be needed. This is also similar to Last Thursdayism.
- [Cueball sits at a computer, staring at the screen and rubbing his chin in thought. A friend stands behind him.]
- Cueball: Weird - My code's crashing when given pre-1970 dates.
- Friend [pointing at the computer]: Epoch fail!