They refer to “shoo fly pie”, which inferred it had enough sugar and organics within to attract lots flies (Note: there is a set of recipes for shoo fly pie).

Expansion on this function branched out into other references, like shoo-ing someone out of your office.

You can also shew-in (check spelling) a new year, a new dynamic, which is used similarly to “show-in”

1. verb–word to scare away dogs, cats, chickens, etc.

2.to drive away by saying or shouting “SHOO!!”

3.to request or force someone to leave–“I’ll have to shoo you out of here now.”

4. a “shoo-in” is an easy winner as in politics.

5. “shoo-fly”–admonition or threat to an insect pest

6. to chase away