I'll tell you how the game works with examples
Poster 1 types: (insert object here) plus
Poster 2 types: (insert a different object here) equals
Poster 3 types: (insert the product of combining the first two objects here)
Poster 4 does the same thing as poster 1
Poster 5 does the same thing as poster 2
Note that Poster 3 could just use an object that has features from both objects, or he/she can just post some random item.