1. To arrive in a particular vehicle. The phrase "to (something)" can be used between "rock" and "up." I hate when my dad rocks up in his clunky old van to pick me up from school. They rocked up to the party in a stretch limousine.

2. To arrive wearing a particular outfit. The phrase "to (something)" can be used between "rock" and "up." He rocked up to the party in a bizarre floral-print tuxedo. Make sure you budget enough money and time to find a wedding dress you're happy with. You don't want to rock up in something you end up regretting later on.