I found this applies more the older you get I think. Personally, get stuff done during the week, come the weekend, it's the beach, dinner / bars, remodeling, bike ride, etc... The harder I work during the week, the more I do on the weekend that absolutely doesn't involve programming.
Keep in mind, if stuff needs to get done, it needs to get done - happened to me just this last Friday - went to dinner with the wife and parents - got a phone call from my partner about an event we were having saturday and a change needed to be made on the website. So I finished dinner, ran home (20 minute drive) made the change, then went back out to meet friends. Normally, I would have brought my laptop to dinner and left it in the car for this specific reason but I guess I thought I could get away for an hour or 2. Nope!
Anyways - I've heard "work hard play hard" intermixed with the term "weekend warrior" - someone that spends the week in an office and on the weekend, just disappears a bender. Everyone has their idea of fun.
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Basically it means that you'll work either twice as hard, or twice as much as a standard worker.
If your lucky the company might schedule outings for the entire company on the weekends. Which would be nice because who doesn't want to spend their free time off the clock with the same people they're working with 60+ hr/wk?