"Rock up" is a colloquial expression that refers to the act of arriving at a place or event, often suddenly or unexpectedly. There are many synonyms for this term that can be used in different contexts. Some common alternatives include "show up," "turn up," "appear," "arrive," "come," "roll in," "drop in," "pop in," "make an entrance," "pull in," "materialize," and "surface." Each of these synonyms has a slightly different nuance and connotation, so it's important to choose the most appropriate one for the situation at hand. Whether you're describing a surprise visit from a friend or a dramatic entrance at a party, there's sure to be a synonym for "rock up" that fits the bill.