Gwen: Great job, Joe, you only had one job - water the plants.
Joe: I did.
Gwen: I don't think so. I just got back home and they look pretty dead to me.
Joe: They were absolutely fine yesterday. I watered them just like you told me.
Gwen: It's a desert, Joe.
Joe: What am I supposed to tell you, Mum? Maybe there was something wrong with the water.
Gwen: Which watering can have you used?
Joe: Green one.
Gwen: Aha, thanks Joe. We don't have a green watering can.
Joe didn't water the plants and killed them. 