The rules are simple: Post a picture that people might not know what it is.
Then, if the next poster, knows what it is, they will say what it is, and then they post another weird or obscure picture.
If not, then they will say "WHAT IS THAAAAT?!" and the previous poster will tell them, and post another picture. This cycle will repeat until some gets it right.
I'll start:
(Note: it does NOT have to be KSP related. This is a Lounge sub-forum, isn't it?