It's Always Sunny in Philadelphia Season 16 Revamps Charlie's Apartment

Frank eventually discovers that the room to the right of the TV is actually a bathroom with a toilet and what looks like a sink. There's all sorts of stuff stuck in there, like Charlie used it as a closet and forgot about it, but Frank is more focused on the toilet. Charlie insists it's a bad toilet because it "runs all the time", but given the whole situation they're used to, that's a pretty ridiculous reason not to use a toilet. This sends Frank to search for more coins, and the one behind the griddle turns out to be a giant, empty room. It's probably the master bedroom of the apartment, and it's empty. Frank is once again furious that they could have lived in less cramped quarters, but Charlie seems to like things the way they are.

In the end, Frank agrees to close both doors once again in a deal with Charlie, bringing things back to the way they have been for 14 seasons, but the existence of the two pieces ends up creating more questions than answers. Way back in Season 1, more of these doors were open, and there's potentially conflicting information.