Every single character in Earthworm Jim 2 is a cow.At the end it turns out that three main characters are cows. In Udderly Abducted, there are flowers that turn into cows. So why other characters can't be cows? The Level Ate boss is literally a steak, so he was a cow in the past. Level 4 may be a cow's bowel, since as we all know, cows may suffer from parasitic worms. At the end of each level we see cows congratulating us, but each level takes place in different location, so it's different cows, not the same! Why it's always cows? Because there's nothing but cows in this world.
WMG / Earthworm Jim
Nintendo Hard levels to defeat a female alien antagonist (Queen Slug-for-a-butt and Mother Brain, respectively). In the ending, they are both revealed to be female (cows are females, bulls are males).