它是一个像大头钉一样的小东西。

It's a small object resembling a pin.

如果扎进一颗大头钉，气球就会突然爆开。

The balloon will pop if you put a pin in it.

使用镀锌的大头钉，开始把第一层毛毡钉在甲板上。

Using galvanised clout nails with large heads, start to nail the first layer of felt onto the decking.

乔用锤子把一只大头钉敲进墙中用来挂一幅画。

Joe hammer a tack into the wall to hang a picture.

为了固定领带，他拿起黑板擦，把一个大头钉透过领带砸入他的胸膛。

Trying to fix the tie , he took a blackboard eraser and hammered a large tack through his tie into his chest.