“Mallyhacked” - meaning something that is broken or destroyed. I heard this phrase a lot from older folks during my childhood, but never by anyone who wasn’t from my area. My SO didn’t believe it was a real word so I did some digging and I think that it is likely a very regionally accented version of “malahack”.
Urban Dictionary says that malahack comes from the Lumbee-English slang of southern North Carolina. I don’t think that’s quite accurate because I’m not from anywhere close to North Carolina. My preferred reference is from The Vocabulary of East-Anglia: An Attempt to Record the Vulgar Tongue of the Twin Sister Counties Norfolk and Suffolk, as it Existed in the Last Twenty Years of the Eighteenth Century, and Still Exists: with Proof of Its Antiquity from Etymology and Authority; in Two Volumes · Volume 2 by Robert Forby, 1830:
Malahack, v. A word ludicrously fabricated, which means to cut or carve in an awkward and slovenly manner.
Dangerous in what way? According to the article: