dry and boring, and rather stiff
Depends where. Only one is slightly amusing though. Other accounts sound staccato when speaking English, though when speaking Polish, Podlaski accents are melodious and Poznanski accents nasal.
The slightly funny one is sometimes when people from certain parts of upper Silesia speak English at B2/C1 level and sound rather like characters in South Park. Perhaps there was a lot of immigration from there to Colorado.
If you want to make fun of Poles
A sign of a mature and confident nation rather than a minor place of cultural cringe is not caring when others make fun. Another one is not assuming that others know or understand about things in Poland. It isn't Shangri-La that nobody's heard of and people for their own opinions regardless of any point of view that is being put to them.
A lot of discussion here. Terms like Limey, Yank, 'Merkin, Kraut, Gerry etc are nicknames, often with military origins. None of them are used as terms of abuse or to denigrate. Polak is a word in Polish, not slang nor a nickname and likewise not used to abuse or denigrate..
Important to separate it from the American slang word Pollack which people say is abusive and used negatively.