I'd drop major hints that i know who he is. Like listening to my ipod really loud and singing along to Grace kelly, then oredering chicken, then 'knitting' a big M and finally playing with my tamagotchi. I would talk to the tama and say 'Oh Mika (it's name) you're getting so big now!'
After all that Mika would be like and i would just simply smile and say 'Hi'
That would start a conversation... surely!
Thats if he doesn't ask to switch seats with someone...