1. To cause something to become wrinkled or creased. A noun or pronoun can be used between "rumple" and "up." Make sure you don't rumple up your shirt before your interview tomorrow! Don't toss your clothes in a heap like that—you'll rumple them up!

2. To physically assault someone; to beat someone up. A noun or pronoun can be used between "rumple" and "up." The mob boss sent a couple goons over to rumple the accountant up so that he would be too scared to testify. A group of older boys rumpled me up a bit because I wore a pink shirt to school.