Don't be ridiculous, that would never pass QA.

But this one will. Joy for years to come:

public string GetDayOfWeek(DateTime date) {
    return ((date - new DateTime(1970, 1, 1)).Milliseconds / 86400000) % 7 switch {
        0 => "Thursday",
        1 => "Friday",
        2 => "Saturday",
        3 => "Sunday",
        4 => "Monday"
    };
}