jack-o'-lantern=南瓜灯,jack-in-the-box=打开盖子就跳出玩偶的整人玩具,jack-in-office=自命不凡的小职员,jackknife=可以折叠的刀,jack-of-all-trades=百事通,Union Jack=英国国旗,jack potato=带皮煮的土豆,无奖竞猜——>jack of hearts=?
jack of hearts
I don't know it means, but i think it doesn't translate it from literally.
"Jack" is often saw in many sentences, it seems that foreigners very like it.