Any and all jokes/cheap shots about Ryuujou's lack of breasts, whether saying she's like a destroyer, messing with her flat chest, her getting messed with by boobs, gags that require boobs (like rei no himo), just plain insulting her lack of breasts, or suddenly - breasts but with some mean joke attached.

Please don't include pics where she's just envying others' breasts and there's no punchline; those can be found easily with "ryuujou_(kancolle) breast_envy" (if there's a decent punchline it's okay).

Pixiv Tag for images that joke about Ryuujou: RJいじめ (Bullying RJ)

For the opposite, see pool #12023.