Pinyin "huai4"

In MandarinBanana's mnemonic system, the Pinyin syllable "huai4" is split up into two parts: "hu" and "ai4". You can visit the Pinyin index to see how other Pinyin syllables are split up into initials and finals.

Mnemonics for Pinyin initial "hu"

Hu is for Helga Horse.

Mnemonics for Pinyin final "ai4"

In the airplane's bathroom.

Characters pronounced huai4

坏
壞
huài = hu + ai4
bad / spoiled / broken / to break down / (suffix) to the utmost
坏 = 不 + 土 : In the airplane's bathroom, there is a clear sign that it is forbidden to enter the room with dirty feet. Helga Horse is quite spoiled though, so she enters right after she went to the muddy stables and spreads dirt all around.
壊
huài = hu + ai4
Japanese variant of 壞|坏[huai4]