explanation :
Something, usually a quick drink or snack, that provides a burst of energy or restores your nerves.  People may say they need a 'pick-me-up' if they are having a long, busy day and need to renew their energy.  A pick-me-up might be a cup of coffee or Coke or a candy bar.

e.g. I've been out with the kids all day.  Before going to the concert, I could use a quick pick-me-up.