As a Protestant, I’ve never thought of Carnival as part of the liturgical calendar, but I’ve heard it referred to several times in the last few weeks, often as part of Polish school activities. As the festive time before Lent, Carnival includes Fat Thursday (marking the last week before Ash Wednesday).
The Polish tradition includes eating pączki, similar to a jelly doughnut. My friend Klaudia told me that the most authentic filling is a rose jam, and that Poles also put this rose jam in tea. I couldn’t find anything rose in the the jam/jelly aisle at the supermarket, so I tried tea with a jam that I had in the fridge and it was wonderful, much more fruity than fruit flavored teas.