Everyone who can run, jump, and swim are already over here.
He'd be an illegal alien.
Because there's only Juan Cena
They ran out of san storage
It runs in his jeans.
Pier pressure
Because he higher and higher. (I translated the joke from Dutch, and yeah it's supposed to not make any sense, it just sounds funny, in Dutch at least. :-$)
Because all the one that can run, jump, or swim are already in the US.