To get "smart" with another person. To have an attitude. To be wearing smartpants. To be a smartass.
Caitlin: You've been neglecting me all week! Why did you blow me off yesterday?! What were you doing that was so important??
Jeffrey: I had to watch American Idol, and I had to go tanning! And I had to play volleyball! And I had to buy pants from Victoria's Secret for $9.99!! And I had to go to Bath & Body Works with Lisa.
Jeffrey: I've been busy!
Jeffrey: How come you didn't pick up my phone calls last night?
Caitlin: I was "busy"
Jeffrey(with smartass attitude): Oh, why didn't you just send me a text stating you were busy. It would have been understandable
Caitlin: ::angry face::
Jeffrey: Am I getting fresh?