His Body Language- when he's around you and he says or does something funny and everyone laughs, his eyes might flicker to you for a second to see if you laughed too. Eye Contact- a guy who is interested in you may take his chance and look at you a lot. He may try to catch your eye, or if he's shy he my suddenly break his gaze if you catch him checking you out. The Way He Speaks- if he playfully teases you a lot this can be a sign that he's flirting with you and wants you to flirt back!