high five. down low. too slow.

Someone asks you to "high five"--to tap the palm of their hand with your same hand over your heads as you face one another. After that, they will say "down low". This means they are asking you to "high five" or tap the palm of their hand with the palm of your hand down lower--about waist high--as they extend their hand out toward you. Tap the palm of their hand with your same hand again. If you don't respond timely they may take their hand away and say "too slow" then laugh.