FYI

My neighbor recently returned from a trip to Costa Rica. He played a lot of poker at the Horseshoe Casino there. He had something happen to him that I was not aware was a rule in some casinos.
He was in a 2/5 no limit cash game and bought in for $600 which seemed to be what most of the larger stacks at the table had. He found the action to be fairly weak and loose and he sat back and waited for a few strong starting hands and rather quickly doubled up. He then busted another player and was sitting with $1,800 or so within an hour. He got a little looser and braver as he felt like a huge stack at the table that could push the table around a bit. He locked up in a hand with a guy that looked to have about $400 in front of him and flopped middle pair. He decided to just put the guy all in so he shoved. What he didn't notice was that the guy had $2,000 in cash sitting behind his stack in $100 bills. The guy flipped a set and the $1,800 was gone just like that. Licking his wounds he went to his hotel and regrouped. The next day he came back to the same game and sat down. This time he put $4,000 in twenty dollar bills behind his $600 in chips and got down to business. He got in to a hand with the same guy that had won his $1,800 the night before and had quads. The other guy had a boat and pushed all in with about $1,500. Z-Man quickly called with his quads and flipped them up. The dealer counted $600 out of the other guys stack and pushed it to Z-Man. Z held up the $4,000 in twenties and the dealer said, "Only 100 dollar bills play, no twenties."
I checked with MiamiDon and he confirmed that this holds true at casinos in Vegas as well. He said that some don't play cash at all but the ones that do it's hundreds only.
I was not aware of this and as much as I play I guessed that some others out there would want to know this before it happens to them.