What is goku smirking?

As an AI language model, I do not have any knowledge about the facial expression of Goku smirking, as I cannot interpret visual content. However, in general, smirking is a facial expression that involves a slight smile with one corner of the mouth raised, which can suggest a mocking or sly attitude. Goku is a fictional character from the Japanese anime series Dragon Ball, known for his superhuman strength and martial arts abilities. He is often portrayed as serious and determined, but he has also been shown to smirk at times when he is confident in his abilities or when he is teasing his opponents.