Minecraft Wiki
  1. Creeper Morph: can knockback you.
  2. Tnt: same as creeper morph.
  3. Floating Jukeboxs: you can get knocked off.
  4. Getting too close to a treasure chest: same as creeper morph and tnt.
  5. The UHC "Opening in minutes..." thing: it can blind you, and make you crash into walls, or can make you go into the void.
  6. GG spaming: may lag the server. (eg. getting a rank upgrade from a chest causes alot of players saying "gg" that might lag the server)

UNFINISHED!