catch someone red-handed
US /kætʃ ˈsʌm.wʌn ˌredˈhæn.dɪd/
UK /kætʃ ˈsʌm.wʌn ˌredˈhæn.dɪd/

1.
當場抓住, 抓個正著
to discover someone in the act of doing something wrong or illegal
:
•
The police caught the thief red-handed as he was trying to break into the car.
警察當場抓住了小偷,當時他正試圖闖入汽車。
•
My mom caught me red-handed eating cookies before dinner.
我媽媽當場抓住了我,當時我正在晚飯前吃餅乾。