obviously they two are making a competition with the 倒立.
倒立 means stand upside down (with your hands)
to keep balance, 小柱子 puts his feet against a tree. But 二福 doesn't. It means 二福 can keep balance on his own. This is harder.-----靠树的倒立 vs 不靠树的倒立
I said it was a competition because this word: 还
In this case, 还 means repay / fight back
for example,
我军昨天刚刚夺取了这片阵地,今天敌人就立刻还了我们一个大反击。
there is a 成语:还以颜色
颜色 means color. it has another meaning: 厉害
for example, someone hits you. you could say: 我要给你点颜色看看. Then you kill him~~~lol