All two cycle engines mix oil with the gasoline. The oil greatly reduces wear between engine parts. Without lubricating oil, an engine would run only a few minutes. Some newer outboard motors have oil injectors that measure the proper amount of oil into the gas and air mixture, but most still rely on the boat operator to mix the gas and oil properly.
Some people are careful to mix their gas and oil.
Others are careless. I once saw a fellow pour oil into five gallons of gasoline and head up the river. He didn't shake the tank. When I later asked him about it, he said the waves and bouncing of the boat mixed the gas for him. This presented a scientific question.