"Up" is a simple word that has a plethora of antonyms. The phrase "on up up" could mean something that is improving consistently, but its opposite would be "on down down." This would signify something that is deteriorating with each passing day. Another antonym could be "down low," which refers to something that is concealed or kept hidden. Similarly, "down below" denotes something that is situated at a lower level or beneath the surface. The term "down and out" could also stand in sharp contrast to "on up up," indicating someone who is destitute or experiencing a significant setback.