One of my favorite school-related stories is when the math teacher I worked alongside two years ago had to call home on a student.
Person on other end of the line: Hello?
Math teacher: Hello. This is Math Teacher calling from So-and-So High school, may I speak to Not-Too-Bright's mother, please?
Person: Uh. She's not here right now.
Math teacher: Oh. Who is this?
Person/Obviously Not-Too-Bright himself: Uncle.
Math teacher: I'm sorry, who?
Not-Too-Bright: Uncle. Uncle.
Math teacher: Who? Whose uncle?
Not-Too-Bright: MY uncle.
Realization dawns, and Not-Too-Bright hangs up.