Is "sexual arousal" physical stimulation or something as simple as an erection?
Sexual arousal are the things that take place as the desire for sex increases. Physical touching can cause arousal, as can things seen or words heard. For males, sexual arousal is seen initially by the erection of the penis and the flow of pre-ejaculate fluid from the penis. There are other markers of increasing sexual desire, such as the skin flushing, due to the increased blood pressure to get the penis erect, the drawing up of the scrotum, and the erection of the nipples. These signs are not the sexual arousal itself, but the consequence of being aroused.