"Don't pass the buck" IS an idiom. It means don't pass along the responsibility.

Pass the Buck - 2002 is rated/received certificates of:

Australia:G

Pass the Buck - Australian game show - ended in 2002.

Do not pass the buck means to not pass off your responsibility onto others; or simply, do not say, "I will go get someone else to do it."

To pass the buck means to pass the responsibility for something on to someone else. The saying originated from poker, where the buck was the marker that indicated whose deal it was. Passing it meant passing the responsibility for the deal.