Switch case ,Default,run

Hai
Is it possible to run some function which is in other cases in c#
Ex:
switch (aa)

{
case 1 : Messagbox.show("a");
break;

case 2:
Messagbox.show("b");
break;
case 3
Messagbox.show("c");
break;
case 4:
Messagbox.show("d");
break;
case 5:
Messagbox.show("a");
break;
..etc
default:
//Here should run case 1,case 2,case 3,...etc
break;

}


Thanks