Smith being funny

Ok...if smith is a computer program, how could he be so damn funny/sarcastic/cynical? Take from the M3 trailer... 'Welcome back Mr. Anderson....we Missed you." it makes me laugh every time i see it...but computers wouldnt be programmed with emotions would they?

he's evolving. hes a program that learns thru each experience and evolves, intuitive. And its become so advanced he's almost becomming human

hahaha smiddy is always funny without necissarily trying to be funny its just the kinda guy he is