Yes. Sustained eye contact that last slightly longer than normal.
In related news, today this guy was totally checking me out while pretending to read at Barnes & Noble. And then we eventually made eye contact and his entire body suddenly jerked as he tried to pretend nothing was up. He was obviously extremely anxious (possibly closeted?).
I'm not entirely sure about that. I think only certain gays do that "look".
If a guy up and downs me I usually assume he's the thirsty kind.
Omg your avi I'm in love with Olly's ass
-------------
Making eye contact while you're walking on the street is the easiest way to find out if a guy is gay, I just find it SO easy even tho I don't know how to explain the gay "look"