cheep, v. — Green’s Dictionary of Slang

cheep v.

[SE cheep, a faint, shrill sound, esp. of a young bird]

to inform on, to complain.

1906		J.W. Carr ‘Words from Northwest Arkansas’ in DN III:ii 130: cheep, v. To betray a secret.
1920		Ade Hand-made Fables 57: If she wanted to call all Bets off and declare a new Book, he would be Game and never Cheep.