Do you mean the BREAK; ?
I know in C++, you can say,
Because case1 doesn't have break, case1 will do both somthing1 and something2, then finally break; You cannot do this on C# for sure because you are required to have break;. But, basically that's the word. If you break, you break the entire switch statement, it wouldn't make sense to even see the second Case9 as it already break.