Shivering during urination

Have you ever wondered why sometimes when you are urinating, you suddenly shiver?

When I was in the toilet with a friend of mine, he told me that his father actually has a theory for this. And he told me this while we were urinating. Anyway, his father suggests that sometimes when we discharge urine from our body system, our body temperature decreases. Thus our body's natural reaction would be to shiver to gain heat. I'm actually not quite sure how accurate is this, but it sounds quite scientifically logical.

This isn't a problem for girls, because they always use the cubicle. However for guys, it would be quite embarrassing if you suddenly shiver while using the urinal.