He was ratfinking his accomplices to avoid prison.

Rather than confront his coworkers, Tim ratfinks them to the manager at the first sign of trouble.

The old mechanic shook his head whenever those ratfinks rolled into town in their noisy hot rods.

If you ratfink me to the boss, I won't be able to keep my job.

Everyone in the crew suspected there was a ratfink feeding information to the rival gang.

Nobody wanted to trust him after he ratfinked to the boss about the missing money.