fly-poster       
noun [ C ] UK uk/ˈflaɪˌpəʊ.stər/ us/ˈflaɪˌpoʊ.stɚ/
 非法张贴的海报传单
a political or other poster (= notice) illegally stuck on a public wall, fence, etc.
  They were putting up fly-posters for the demo. 他们正在为示威非法张贴宣传海报。 
 Fly-posters were stuck to every bus stop and lamppost. 每个公共汽车站和灯柱上都非法地贴满了传单海报。 
 See: fly-posting
 - More examples
 - The wall was covered in fly-posters.
 - Someone had pasted a fly-poster to the trunk of the tree.
 - Has a bill sticker or fly-poster ever been prosecuted?
 - A notice stuck to the station wall got more attenction than the fly-poster who placed it there ever expected.