G-gal, i understand that sometimes a guy do look at other guys, but maybe for very different reasons as compared to gals lah. For me, it would be when:
1) i noticed there's this gorgeous lady, and in the corner of my eye, there's a guy beside her. So, just glanced over at the lucky man.
2) i noticed there's this chio convertible or sports coupe, and if it happens to be a guy, i tried to figure out if it is a young chap or a old man.
Hahaha.....
(I shall assume ah siao is an exceptional breed among the male species... =P)