late 14c., "to make oneself trim or smart," perhaps from Old North French perquer "to perch" (Modern French percher; see perch (n.1)), on notion of a bird preening its plumage. Sense of "raise oneself briskly" is first attested 1520s; perk up "recover liveliness" is from 1650s. Related: Perked; perking.
[origin uncertain; perhaps related to perch, and semantically to the notion of being placed high]
Percolated coffee (1950s+)
To run smoothly and well; percolate: The project's perking now (1925+)
Extra money, privileges, fringe benefits, etc, pertaining to a job or assignment: His men were delighted to be in Afghanistan, he said, mostly because of the perks
[1824+; fr perquisite]