Lower, lower!

You gotta wait for it!

Sure, he avoids looking at him. For shame? Or maybe it's the fear that he might like that and because of that it makes you want to stop being heterosexual. That is what the study of Alfred Kinsey and his spectrum of sexuality talk about, in reality in sexuality there is only bisexuality but due to prejudices and social, religious or cultural constructions we all place ourselves at some point on that spectrum of bisexuality.
That is why it is very likely that most of those who feel so ashamed, afraid or disgusted about seeing people of the same gender naked, or doing sexual acts with others of the same gender, is because it is actually fear and insecurity about that perhaps he may like that but he has it ingrained as something bad. Perhaps it even means that important desires are being repressed, since the three big blocks that the conscious mind uses to block repressed desires from the unconscious are shame, fear and disgust. That is why the greater or exaggerated the demonstration or feeling of disgust, shame or fear towards something, then probably just as intense is what is being repressed. The block must be as big as the desire in order to be blocked.