Stroppy describes someone who is in a bad mood and shows it — snapping at people, refusing to cooperate, taking offence at nothing much. It is British, informal, and very common in speech, hardly ever in formal writing. The classic use is about teenagers ('a stroppy fifteen-year-old'), and about anyone acting like one: a stroppy customer, a stroppy waiter, a stroppy email. You can 'get stroppy' or 'turn stroppy' when something annoys you. The tone matters. It is not a strong insult — it is closer to teasing, and friends say it to each other. But it is dismissive, and it is worth noticing who tends to get called it: women who complain firmly are called stroppy far more often than men doing the same thing, and the word can quietly turn a reasonable objection into a mood. So it is a useful word to understand and a word to use with some care. Americans mostly do not say it.

愛鬧脾氣的、動不動就不爽頂嘴的。英式口語，講青少年最常用；語氣沒有很重，但有點看不起對方「在鬧脾氣」的意思。不是「兇」也不是「壞」，比較接近台灣說的「番」、「在鬧」。