be caught in the act
To be seen, and perhaps apprehended, while doing something (often something nefarious). The burglar was caught in the act by our security cameras. I'll never forget trying to steal a cookie and being caught in the act by my grandmother—she took it and ate it herself!
be caught in the act
COMMON If you are caught in the act, someone sees you doing something secret or wrong. The men were caught in the act of digging up buried explosives. Note: In this expression, `act' refers to the act of doing something.