Yes this is a good joke until you realize there is no other way to get some level of type safety in PHP other than adding a bunch of unnecessary classes.
That's like saying the only way you can get your car to remain buoyant over water is attaching a huge flotation rig to it and even then it won't be as fast as driving on the road
Strong typing and dynamic typing are orthogonal. You can have the former and ignore the latter - see Python - and you can completely forget about both - see PHP.