This needs to be emphasized:

A lot of this scenario (how he will react, etc) depends on your history with this bookie? Are you a consistent square loser customer for him? Or has he paid you out the last couple times you guys met up? Because NOTHING pisses off a local more than a guy that has gotten paid out but then has no money when it's time to pay in. If that's the case, you've got 2 weekdays left to beg, borrow or steal that money to get the 3500 or as close to it as possible.

If, on the other hand, you're a consistent loser, then as others have said, you need to scrounge together everything you have and give it to him, and offer to pay at least that much or more every week from here on out. Some folks have said "take your last $500 and give it to him," but if I read your post correctly, that is $500 in credit, not $500 cash money you have in your pocket. So you really don't even 'have' that money per se, it's just available credit that you technically could use to try to dig out of the hole a little bit. Unfortunately, that's where most gamblers go wrong, because always remember: to get out of a hole, the first thing you have to do is stop digging. If you try to chase a -$3500 balance with $500 credit, you will NOT be successful.

Bottom line: most bookies, since they operate in a legal gray area, are actually more principled and old school than you think. They are very big on your/their word, honesty, and integrity, believe it or not. The absolute best thing you can do is scrape together absolutely every bit of cash you can, via selling things on craigslist, pawning them, cc advances, etc., over the next couple days, and then call the guy on Saturday and basically say, "hey man, wanted to give you a heads up that i got a bit carried away and blew some money i didn't have, thinking i'd win a few more games. Instead of trying to chase with the last $500 in credit and losing it too, i spent the last couple days pawning and craigslisting stuff and have $X.XX to pay you on Monday. I should be able to do about that much each week, more or less, until the 3500 is paid off. I'll make this right."

You will be AMAZED at the local's reaction, and i guarantee you that you'll instantly score 'integrity' points with him and he definitely won't do anything crazy or try to intimidate you. BUT...if you blow that last $500 trying to chase, it will be OBVIOUS that you never had that money nor did you have any intentions of paying it, and were simply taking advantage of him to try to claw your way back. That, my friend, is what really pisses locals off.

But again, all of this depends on whether or not he has paid you out or you have paid him (and how much) the last couple times you met. If you can answer that question, I can provide you with a more succinct answer.