It was friday evening and almost everyone in office had left. I was assigned a bug related to some of my code changes. I called my senior to help me debug (has three years of experience, whereas me having only one year exp, who is also a very good friend of mine *always helps in debugging*).
So the code goes

switch (someEnum) {
case One:
doSomething()
// no break
case Two:
t.x = someEnum
break
case Three:
.....
}

I had recently added new enun One and was reciting the code logic to him as we were looking through code.
Him: Hey you haven't set t.x in case One. How did you miss that?
Me: No look, I haven't but a break on it. It will go ahead and set it in next case.
Him: What are you talking about? if the someEnun is One why would it execute Two case. Lets copy that line up there and try it locally.
Me: No no no wait. Are you saying that groovy doesn't need breaks in switch (Me being new to groovy but good with Java).
Him: Why would you need break in switch case even in Java?
Me: *stares at him*
Him: I'm going to execute a psvm right freaking now.
Me: *while he writes the psvm* Why did you think there were breaks in switch in any code?
Him: Shut up. *writes psvm code cursing me everywhere*
*executes code*
No way. Really??
Me: Tell me why do you think are there breaks in switch.
Him: I though they were to get you out of switch block and not execute the default block.
Me: So were you coding switch until now without breaks?
Him: I don't know man. I'm starting to doubt all the switches I have ever written.
Me: Anyway that's not the problem, so moving on.
*a while later*
Him: If a interviewer would ask me how would you rate yourself in Java. I would be like "Well I worked on various projects for 3 years in Java, but didnt know why we put breaks in switch. So you figure it out yourself."

One of the best moments in office.