Hello everyone! I was talking to a Polish person and the phrase dać klapsa came up. Then I wondered when the masculine noun is supposed to end in -a and when no ending. I asked her if you'd say sierpa and she says it doesn't sound well and it's rather sierp in the accusative, then we tried several other nouns and tried two websites that decline nouns. There was disagreement regarding some words, one website says that, for example, kompas takes no ending in the accusative while the other says it takes -a, the same happened with plecak, but other nouns didn't take -a. Now both of us are confused. Is there any rule of some kind to know when to put -a for masculine nouns in the accusative and when to use nothing, or is it possible to add -a as optional? Thank you in advance!