1. Friday the 13th is a bad day. 13號星期五不吉利(黑色星期五)
The reason that Friday 13th in particular is unlucky is due to the massacre of the Knights Templar by Phillip IV of France on Friday the 13th.
2. Bird pooing on you is good luck. 鳥糞掉身上是走運的象徵
One theory of this is the sort of karma logic that assumes, if something bad happens to you, then something good must happen to balance out the karma.
3. A black cat crossing your path is considered bad luck.
In the old, superstitious days, witches could transform themselves into black cats. If one crossed your path, it meant a witch was watching you.
4. Atchoo (bless you) 有人打噴嚏(要對他說上帝保佑你)
This comes from a plague that was spreading in 590 A.D. Italy where most people who sneezed would die. The pope urged others to bless such people and pray for them that they might become better.
5. Crossing your fingers to wish for good luck 交叉手指期盼好運
One theory of this is that during the Hundred Years War between France and England, archers would cross their fingers before pulling the bow string in order to grant them good luck. Before that, it was also a secret sign between members of Christianity (when it was illegal).
6. Never take the third light from a match, it's bad luck.
In World War I, snipers sometimes operated at night. Their technique involved waiting for someone to strike a match to light a cigarette; on spotting the light they'd train a scope on them. On the second light, the sniper would focus his shot, zooming in ready for the kill, on the third light, he would fire, killing the person who lit the match.
7. Walking underneath a ladder is widely held to be bad luck.
'Walking under a ladder' came about in England a few centuries ago when people drank more ale at lunch than ate food. Drunken sign painters were likely to dump a bucket of paint if you walked by or under their ladder and handymen would drop tools.
8. Broken mirror will result in seven years bad luck.
Breaking a mirror is bad luck because at one time mirrors were very expensive. If a palace maid broke a mirror she was sentenced to 7 years in prison.
9. Carrots help you see in the dark. 胡蘿蔔有助於提高夜視能力
This was part of World War II propaganda. The British had invented radar and we began bombing the Germans at night. The Germans, confused as to how we bombed them at night, started researching how we were doing it. The British government began to spread the rumor that it was the carrots in our ration packs that helped us see in the dark (Note: "in order" is rarely needed) to put the Germans off our trail. They figured it out eventually, but by that time, the rumor had already stuck.
10. Spilling salt is a bad omen. 鹽灑出來是不吉利的
Spilling salt is bad luck because in Roman times, salt was so valuable that soldiers were paid in salt rather than money. Spilling it was equal to burning money. I'm not sure where throwing a pinch of salt over your left shoulder negates the action of spilling, but I can tell you that it is where the word 'salary' came from.