I love those ideas where designers take something mundane and ordinary and change a simple element in to produce a memorable experience for users. Mind you, the experience may not always be pleasureable, but it engages the user and gives them something to talk about.
Here are some examples:
This elavator looks like it is missing the floor. Also, notice the mirrors on the walls.
These handbags are a lot of fun.
This urinal has an etching of a fly. Guess why? (ok, I agree, this idea is not memorable)
You can see outside, in this toilet in Britain. Would you dare to use it?