When the other person was quicker, this is the sentence: It’s on me next time.
In front of you the hedgehog is running around in the cup with a snake painted around it (it’s). Next to you sits your uncle, who pulls out his card, puts it away again and drinks milk (on me).
You tease him for always drinking milk; in front of him lies a xylophone and behind it a cup (next). Next to the cup lies a clock – or, if you prefer the image with a taste, a tea with milk in it (time).