What is blue in the winter green summer and smells like cheese?

Here's why:

* Blue refers to the characteristic blue veins in blue cheese.

* Winter green summer is a bit of a trick. It refers to the fact that blue cheese is typically made from cow's milk, which is green in the summer (due to the cows eating grass) and winter (due to the cows eating hay).

* Smells like cheese is obvious, as blue cheese is a type of cheese.

Let me know if you'd like to try another riddle!