Oh quotes, be good to me

Economics
This girl who always brings her lunch to class (I hate it) had a soda bottle that was clear with some yellow-ish drink in it. In the middle of his sentence about economics, my teacher stops and says "... I hope this is not what I think it is..."
The girl responded "It's not beer."

Art History
Similarly, my teacher stopped in mid-sentence to say: "Did I do my little dance of the arch yet? No? *puts up hands* I am a dome!"

Filmmaking
Teacher: "What would be the sources of light in this scene?"
Student: "Well, does one of you have an after-sex glow or something?"