We have employees up the gump stump -- meaning "we have a lot of employees." Any clues as to the derivation?

"Gump stump" is a contraction of "Gump stumped by everything", a reviewer's light-hearted assessment of Forrest Gump, the lead character played by Tom Hanks in the 1994 movie of the same name.

Your boss wasn't exactly saying you had "too many" employees. He was saying too many of your employees were as "Gump stumped" as Forrest Gump.