1. To ruin or damage something; to mess up something. In this usage, a noun of pronoun can be used between "mung" and "up." The threat of a hurricane really munged up our vacation plans! Boy, you really munged this engine up. When was the last time you got your oil changed? I munged up my knee in practice last night so I won't be able to play on Saturday.

2. To make a mistake; to mess up. I think I munged up by putting it in the oven too soon. You munged up, Dave. Just admit and we can all move on.

3. To fail or malfunction. The printer munged up last night so I still haven't printed my report. It looks like the carburetor is totally munged up—you'll have to get the whole thing replaced.