Tuples

https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/builtin-types/value-tuples

Native tuples are supported as of v5. Here is an example of how to use them.

var (foo, bar) = db.Single<(string, string)>(@"select 'foo', 'bar'");

Assert.AreEqual(foo, "foo");
Assert.AreEqual(bar, "bar");

You can also do nested tuples as per below.

var data = db.Single<((string foo, int i) first, (string bar, int j) second)>(@"select 'foo', 5, 'bar', 6");

Assert.AreEqual(data.first.foo, "foo");
Assert.AreEqual(data.first.i, 5);
Assert.AreEqual(data.second.bar, "bar");
Assert.AreEqual(data.second.j,  6);

Using tuples for parameters is also supported as below.

var record = (2, "Timmy", 5);
db.Execute("update kids set name = @Item2, age = @Item3 where id = @Item1", record);

Here is the original issue. Thanks to @asztal for the slick contribution.
https://github.com/schotime/NPoco/issues/358