From Parallel Waves or Parallel Inverted Lines.
Circulate; 1/2 Split Circulate; Centers Hinge, Box Circulate
  & Trade as the Ends Circulate twice (around the outside).
Parallel Waves end in Parallel Two-Faced Lines.
Notes:
- 
For historical reasons, Perk Up may occasionally be called from an
    Eight Chain Thru.  The first Circulate is a Pass Thru; the 1/2
    Split Circulate is replaced with Outsides 1/4 Right (or as directed) as Centers
    1/2 Circulate (Touch).  We believe this usage should be avoided.
- 
Dancers often confuse Perk Up with 
    Percolate [C1] 
    since both calls sound similar and start with a Circulate.  In order to help
    other dancers within the square, some dancers yell 'Up' for Perk Up
    and 'O-Late' for Percolate.
anything Perk Up [C2]:
 Do the anything call; then Finish Perk Up (1/2 Split Circulate; Center Line Hinge, Circulate & Trade as Others (Concentric) Circulate twice).  
Usually ends in Parallel Two-Faced Lines.
The anything call replaces the first Circulate.
 
 See also anything Coordinate | Motivate | Percolate | Perk Up [C2].