Here is a bit of doggerel, published in 1889, about when New York catcher “Buck” Ewing starts to “kick,” i.e. to argue with the umpire. What does this use of “peep” mean? My guess is that it has something to do with Ewing taking off his mask, but I can’t figure out the precise meaning of this bit of obsolete slang:
When Ewing strikes an attitude
And liberates his “peep,”
The people on the bleaching boards
Lay down and fall asleep.
The batters all play mumbly-peg:
The umpire feels quite sick.
The players in the field lay down
When “Buck” begins his kick.
He kicks at balls, he kicks at strikes,
He kicks at everything.
When something fails to suit his “nibs,”
His little song he’ll sing.
They tell him this, they tell him that,
But to his tune he’ll stick.
They lose an hour, more or less,
When “Buck” beings to kick.