buckle down/ buckle up
30/01/2013 08:33
Often times, we do say 'buckle up' in place of 'buckle down'.
Buckle up means to fasten one's belt, seat belt, or buckles: She won't start the car until we've all buckled up.
Buckle down means to set to work with vigor; concentrate on one's work: He was by nature a daydreamer and found it hard to buckle down.