Rabbits rely on body language for the majority of their communication. They also rely on manners in a way that would make the Heian Era aristocrats look uncultured. And you don’t get manner dictates like that without ALSO knowing how to be passive-aggressive with them.
Rabbit flops are super vulnerable for a bunny. Their stomachs are exposed and they’re in a position that means if danger shows up they have to waste precious seconds getting up before they can sprint for safety. A rabbit flop means both ‘I’m so happy I can’t contain it’ and ‘I feel so safe I am going to be vulnerable and really let go’. Rabbit owners love seeing it. It means that your bun really does feel that safe around you. It’s a pretty high compliment from an animal that knows everyone’s out to kill them.
it can also be used passive aggressively in the ‘you mean so little to me you’re not even worth acknowledging as existing’. It’s right on the same level as walking into a room and greeting everyone but one person. An enemy rabbit would be a threat. This rabbit? This rabbit isn’t even important enough to be a threat. They’re a nobunny and so I will flop because there is nothing in the area worthy enough to bother being aware of.
To humans it can look very much the same but trust me, the bunnies know exactly which is which.