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:烟头是最常见的海洋垃圾,如果你吸烟,如果你担心口袋里的香烟有异味,你能做的就是购买一个口袋烟灰缸。