I love when they police each other...

Me: Okay, you are ridiculously negative.  I challenge you to enter my class and say something positive each day.
Student: Challenge...accepted!  What do I get if I'm positive?
Me: I'll smile at you instead of yell at you.
Student: Yeah, that's not going to work.  How about candy?  You give me candy every time I say something positive.
Me: Why do you need candy?
Student: Because I don't have lunch money.
Me: Where's your lunch money?
Student: I don't have any.  I'm Spanish, I'm poor.
Student 2: You're whining about being poor, you just lost your candy.