I came across the phrase, someone who wears “a pair of khaki pants inside a manila envelope” in Vanity Fair’s December 1st issue, which came under the headline,”Look at what we love. It’s on fire: Stephen Colbert on Trump trauma, leadership loss.” The lead copy follows:
The late night host is ready for a little less excitement. “If Joe Biden is a pair of khaki pants inside a manila envelope, that would be great.”
I don’t understand what on the earth “someone who is a pair of khaki inside a manila envelope” mean.
No dictionary at hand, nor Google search gives a definition of “pair of khaki pants in manila envelope.” I know it’s a figurative turn of phrase, and my naive guess is it implies someone who behaves just like an average people, though he or she is in upper social hierarchy. But, I’m not sure. Is this a common, well-received phrase? I appreciate if somebody teaches me.