From the Unix & Linux StackExchange:

Q: We've noticed that some of our automatic tests fail when they run at 00:30 but work fine the rest of the day. They fail with the message "gimme gimme gimme" in stderr, which wasn't expected. Why are we getting this output?

A: er, that was my fault, I suggested it. Sorry. Pretty much the whole story is in the commit. The maintainer of man is a good friend of mine, and one day six years ago I jokingly said to him that if you invoke man after midnight it should print "gimme gimme gimme", because of the Abba song called "Gimme gimme gimme a man after midnight”… Well, he did actually put it in, a few people were amused to discover it, and we mostly forgot about it until today...