Go away; leave; stop bothering me. Example ... Flying a kite is an activity that should keep them busy for a while so that you can get your 'work' done.
So when someone tells you that catch phrase they are not being serious they actually mean leave them alone.
Other catch phrases :
Get a leg up ...To get a boost or advantage
Get one's goat...To make an angry and emotional response to aggravate, irritate upset or annoy.
Get The Gist... To understand basics or fundamentals
Get the kinks out of ...to get rid of difficulties
Get your dander up..to flare a temper