public void DoSomething(params object[] myParam)
{
}

// ...

object[] foo = // ...
// Because an object[] is also an object, the compiler treats foo as the first element
// of the params array, rather than the params array itself.
DoSomething(foo);

public void DoSomething(params string[] myParam)
{
}

// ...

string[] foo = // ...

// The compiler treats foo as the params array, rather than the first element of the params array.
DoSomething(foo);