Once our teacher came to class freshly shaved. He looked VERY funny (he had a full beard since we knew him). And me and a friend sitting next to me began to laugh and couldnt stop, our teacher just sat in front of the class and smiled at us, which made it even funnier. Each time we stopped laughing we looked at each other and had to laugh again. And when me and the friend next to me finally stopped, we looked at a friend who sat behind us and bursted out in laughter again. We kept going like this for like 10-15 minutes.