Last time on our bassoon care series I talked about the different types of cases available for bassoons and how well they protect the instrument. The other time our bassoon needs some basic protection is when we're leaving it along, but not in the case. Unfortunately for us, the bassoon isn't an instrument that you can safely lay down on a chair...
Please don't do this. Ever. Even at home. There are many problems with laying your bassoon down: 1.) water problems - where water will fall into tone holes and into the unlined side of the boot joint, causing all sorts of problems and 2.) it leaves your bassoon exposed to getting easily knocked down by an inadvertent passer-by. And 3.) you end up depressing keys in an unintended way, which can bend a key out of shape or knock key corks out of place.
In a close quarters rehearsal, this is going to get bumped, potentially causing some serious damage from an impact with the floor, or the bocal getting caught on a piece of clothing causing it to bend out of shape. Even if you're at home, the water problem is there. So just don't do this.
The other thing that I've seen is to rest the bassoon in a corner or against a table. The later is just asking for as much trouble as laying your bassoon down, but it's even less stable. The former is OK in a pinch, if the floor is carpeted and therefore keeps the bassoon from slipping. But don't say I didn't warn you if the bassoon still falls down in that situation, best to avoid it.
So a bassoon dedicated instrument stand is the way to go. It holds your bassoon at an appropriate angle, with a stability to avoid tipping, and since the bassoon is tall enough it should hopefully be noticed and avoided by others in the room.
I suggest you take the bocal out of the bassoon if you are leaving it unattended. DO NOT put the bocal upside-down in the bocal receiver as pictured below. You absolutely risk damaging the bocal in an unrepairable way. You can put it in the bell (hanging from the S-curve with the cork sticking out) when you have the bassoon in the stand. Don't carry it around this way though. The best place for the bocal is back in your case.