小狗开心地摇着尾巴，还转着圈追自己的屁股。

The puppy wagged its tail happily and spun around chasing its own ___butt.

他紧握锤柄，用力敲打钉子。

He gripped the ___butt of the hammer and struck the nail hard.

在班上他总是被当作笑柄。

In class, he often becomes the ___butt of jokes.

那只山羊用头撞了篱笆。

The goat ___butted the fence with its head.