strike a false note

blue note

The flatted 5th scale degree in the blues scale.

couldn't carry a note in a bucket

Not musically talented, unable to sing.

false note

Of a remark or narrative, an indication (as discerned by the listener or reader) of untruth, insincerity, or inconsistency.

lightning strike

A (sometimes unofficial) strike by workers with little or no warning.

on strike

Withholding labor as a protest, in order to effect change in management or government.

sour note

A negative aspect to something mostly positive.

strike a blow

To hit; to successfully land a hit.

strike a chord

To elicit a significant reaction, especially one which is favorable or sympathetic.