also: しらばくれる
ichidan verb, intransitive verb
play dumb; feign ignorance; act innocent
Colloquial verb for pretending not to know something, often when one is clearly involved or aware. Carries a nuance of willful denial or evasion.
彼は知っているくせに、しらばっくれて何も言わなかった。
Even though he knew, he played dumb and said nothing.
Stop acting innocent and tell me the truth.