Actually, it fairly often happens when we substitute accusative case for genitive in colloquial speech, and contrariwise.
E.g. 1) "Я хочу (попить) воду"(incorrect) и "Я хочу (попить) воды" (correct);
2) "Я не строю трагедии из произошедшего" (incorrect) и "Я не строю трагедию из произошедшего" (correct);
3) "Я не сделаю упражнения к завтрашнему дню" (incorrect) "Я не сделаю упражнение к завтрашнему дню" (correct);
4) "Я не подам вида"(incorrect), "Я не подам вид"(incorrect) и "Я не подам виду"(correct)
Although, I've given two alternatives (correct or incorrect), all these statements are equally possible. Especially in colloquial speech. And that's ok
Sometimes these mistakes take place because of lack of knowledge about some idioms (like (1) or (4)). Sometimes it happens because people confuse the singular with the plural in rapid speech (like (2) or (3)). Sometimes people deliberately use such old-fashioned folksy language (which didn't have any rules on its own account because of total illiteracy at that time). They do it just for fun or any other reasons