Impossible choices

You get on a bus and go upstairs. At the front of the bus on the left there is an old man who's turned the seats into a stall selling ice-cream and lemonade for buttons and bottle tops. He has a policy that if you high-five him you get two for the price of one. At the back of the bus is a man who has brought three sheep on board with him. The one in the middle is wearing a straw hat, and the ones on either side are eating it.

Where do you sit on the bus?