A very dry sense of humor
Because they have running yolks.
Laughing stalk
Seals.
Salmon Manilla
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 he didn't like the look of the Poles (for this to make sense, pretend the UK election hasn't happened yet)