It is difficult to determine exactly how Goku would react to such a situation since it involves a crossover between two different fictional universes. However, based on Goku's character traits, it is likely that he would be confused and surprised by the sight of Lilac laying on Frieza's shoulder. Goku is well-known for his innocence and naivete, so the concept of Lilac sleeping on Frieza could be seen as unusual and unexpected for him. He might blush due to his lack of understanding of the situation and his tendency to become easily embarrassed in certain scenarios. Additionally, given Goku's strong sense of justice and loyalty towards his friends, if he was aware of Frieza's evil nature, he would likely be alarmed and ready to step in to protect Lilac.