YSK: Cigarette butts are the most common form of marine litter and if you smoke, the best you can do is to purchase a pocket ashtray if you are worried about the smell from cigarettes in your pocket.
from /r/YouShouldKnow
YSK：菸頭是最常見的海洋垃圾，如果你吸菸，如果你擔心口袋裏的香菸有異味，你能做的就是購買一個口袋菸灰缸。