In Math Analysis:
Student: Does anyone watch Lost?
Teacher: Lost? Oh, that's a TV show. I thought you were talking about my Algebrebra 1 class... I'm trying to teach them quadratic functions...

From in class, we can hear someone yell in the hall: Wagner took my balls!!!

Teacher (incredulously), to student: You never read Harold and the Purple Crayon?
Student: Well, sorry, I was reading Machiavelli.

Student: I want to write a children's book: Little children love each other. A lot.

[Guy randomly walks out of the classroom]
Girl [loudly, to class]: That's my boyfriend! [everyone looks at her] Just kidding. That's what I tell my mom whenever we're driving and we see some weird guy.
Teacher: Your mom doesn't know your boyfriend?
Girl's friend: She doesn't have one.
Girl [still talking loudly, to the whole class]l: I wish I had a boyfriend.
Random student, after pause: That's awkward.

In Physics:
Teacher: You can't pull liquid up a straw. There is no such force as suction.
Student: Then what idiot came up with the word???