My brother used to say that to his younger sibling when I’d be looking over his shoulder as he worked on a car, or whatever. He’d hand me something, and say, “Hold this 'bout an hour.”
I said it to my grandson today while helping him get his sneakers on. I untied and loosened the strings, and handed him one, “hold this 'bout an hour”. He giggled, and a lady who was passing by said, “My Dad used to say that to me, too. Wonder where it came from?”