Paul is 20 years old in 1980, but only 15 years old in 1985

Question: Paul is 20 years old in 1980, but only 15 years old in 1985.How is this possible?

Question: What is that thing we buy for eating but cannot eat it?

Question: You build a house and all 4 walls are facing south. Where did you build the house?

Question: What tastes better than it smells?

Question: What goes in the water black and comes out red?

Question: What loses its head in the morning and gets it back at night?