I'm not sure. I don't know the situation around the joke, but it seems that the workers are joking about how much they have to work. Usually people in finance / banking work Monday - Friday. So we might say, "If you go home early on Friday, don't think about coming in on Monday" (because you will not have a job. You will get fired because you left early on Friday). The "joke" here is that the GS workers have to work so much, well beyond the normal work week. They work seven days a week. (They don't REALLY work seven days a week, so the exaggeration is the joke.) If they leave early on Saturday, they won't have a job by Sunday. That's about all I can get from it.

i;m sorry, i don't~

Goldman-Sachs. Anyway, most people in that business go out on Saturday nights and get soooo drunk, that they sleep through Sunday, not waking up till Monday morning and going to work. Should they go home early, and not get drunk, they would wake up Sunday morning and, mistakenly thinking it is Monday, head for work. Think about it.

Simplified a little? At most companies in America we do not work on Saturday or Sunday. At this company you are expected to work very hard. Every day. The joke is a person is working on Saturday - (unusual) at a big company like that. And they are told if they go home early on Saturday - they should consider themselves fired because it is such a bad thing to do... ... so they say "if you go home early on Saturday don't even consider coming back on Sunday" ... (because you should consider yourself fired). Hailey. I don't see the funny in this joke either - and I'm American. Just seems like a mean thing to have someone work very hard on Saturday only to be expected to come back again on Sunday. ~ But some companies have a strange sense of humor. (Don't worry about this 'joke' it's not very important in your learning.

I wrote something, then read what ''Teacher'' says, so my words are just a repetition, please excuse me. I think it emphasizes with a paradoxical situation what an harsh environment same places are for workers: not only they are called on Saturdays, but if they go away early they might loose the job, therefore it will be not useful anymore to show up on Sunday; I don't know where it originated.