hold the fort 

to assume responsibility in another person's absence

Would you hold the fort for me while I go see what happened next door?

hold the fort by The Return of Light Joker November 22, 2010

hold down the fort

1. To keep a fort from flying away when the fort has such a low density that it tends to float off.
2. To take care of a place while someone who is usually there is gone, such as a store or one's home.

When unsure as to which definition should be applied, it can help to judge the person's intelligence - morons usually mean #2. A less moronic term for #2 would be "to hold the fort".

Someone had to stay at the playground and hold down the fort while the anchor weights were being replaced.

hold down the fort by guyboy625 September 29, 2010

hold down the fort

Taking care of the place you're at while others are gone.

As Sandy was leaving work, she said "hold down the fort" to Jill, who was now working alone.

hold down the fort by ButterflyTrixi August 31, 2008