Teachers, what was the best smartass response from a student you have heard?

Student says to Student B, 'Dude, shut the f up.' Staff says to Student A, 'We don't talk that way. In the future, find a more appropriate way of expressing yourself.' Student insists to staff, 'Oh, sorry,' then turns to Student B and says, 'Dude, would you please shut the f up?' Not a teacher, but witnessed as a student: There was literally 30 seconds left of class and my buddy starts to pack up. The teacher didn't seem to mind, but when the bell rang and my buddy got up to leave, the teacher said the classic line: 'The bell doesn't dismiss you, I do.' My buddy just continues to leave, gets in the doorway of the class and says, 'If it decides when I come, it decides when I leave,' and just leaves the class. This was while working with nine-year-olds: We are doing number problems and a kid is having trouble with a sum. The sum is: 'You have 40 sweets, you give half your sweets to your friend. How many sweets do you have now?' I grab 40 counters and say to the kid, 'Here are 40 sweets. If you give me half, how many will you have left?' The kid turns to me and utterly deadpan says, 'I can't give you the sweets. You aren't my friend.'