The moment Su Ming saw the thing, he realized it was the embodiment of fear from Wade's subconscious. In normal reality, cows did not wear clown makeup, much less walk upright while carrying enormous cleavers.
Wade had once said that there were three things he feared, and he had even made a ranking list.
Third place was clowns—any clown, not specifically those from DC. Thanks to certain books and movies, Deadpool believed that everyone wearing clown makeup was a psychopathic serial killer who could never be killed.
So he rather disliked clowns.
Second place was cows. Supposedly, when he stared into a cow's eyes, he found them utterly hollow, giving no hint of what it was thinking.
The unknown brought fear.
As for first place, it was the combination of second and third place—Joker Cow.
The reason was simple: it was both deranged and impossible to understand.
Originally, his attitude toward such things did not quite count as fear. At most, he would take a detour upon seeing one and avoid dealing with it.
There were no Joker Cows in reality. He had made it up himself, just as a joke.
But he had told this ranking list to others too many times, and had recalled and refined the joke countless times in his mind. In the end, he had inadvertently hypnotized himself, making his own subconscious believe that this fear truly existed.
And so, today, within this nightmare, Joker Cow was born.
Besides that, Su Ming believed there was another reason. Deadpool wanted greater popularity, which had made his subconscious believe that he needed an arch-nemesis. Even that so-called ranking list was merely an excuse.
The sales of the "Batwoman" comics were high because Batman and Joker complemented each other, so Deadpool also wanted a Joker as his arch-nemesis.