HE STANDS WITH HIS FEET AND TORSO POINTING TOWARDS YOU.
Even if he isn’t talking directly to you, if he angles his body in your direction, he’s subconsciously telling you that he likes you.
HE MIRRORS YOUR BODY LANGUAGE.
If he is unconsciously copying your hand gestures, you’re probably connected through some kind of alien master brain. Or he just really likes you.
HE SEEMS JITTERY OR NERVOUS.
If he’s usually the confident type but he starts stuttering when he gets around you, congratulations! You officially scare the crap out of him. In a sexy way.