Region: General | Usage example: Fasten your seatbelt; the next quarter is going to be a roller coaster.

Fasten your seatbelt

Meaning

Prepare for a challenging or fast-paced experience.

Used when bracing for intense activity.

Origin notes can vary by region and source; this page gives the commonly reported explanation and usage context.

Air travel advice to buckle up for safety.

Adopted into everyday speech as flying became common.