Slicking up generally means to make something look neat and tidy. However, its antonyms would be words and phrases that describe making something look messy, shabby or untidy. Some of these antonyms for slicking up could be: disheveled, messy, cluttered, unkempt, rough, crumpled or disorganized. A few phrases that are antonyms for slicking up can be: let the place go, leave it as is, leave it in shambles, disarrange or make a mess of. Using antonyms of slicking up can be quite helpful when you need to describe something that is the opposite of all things neat and tidy.