The Big Bang Burger Bar is (or was) built at the very beginning of time. In fact, it was installed just before the beginning of time to enable guests to arrive and, while enjoying a nice meal, watch the beginning of creation itself.
Max Quordlepleen is known to perform here.
Although it was never stated, it is probable true that The Big Bang Burger Bar too has umpteen time rules to enable guests to come back time after time without bumping into themselves, as this would cause no end of embarrassment.
It is only briefly mentioned in The Restaurant at the End of the Universe.