这个英文笑话的笑点在哪？

我也不理解。

Why do the vegetables always invite the mushroom to their parties?

为什么蔬菜总是邀请蘑菇参加聚会？

Because he's such a... fungi!

因为他是这样的…真菌！

Why does he always leave the party early?

他为什么总是早早离开派对？

Because there's never mushroom!

因为从来没有蘑菇！