ugly customer(redirected from an ugly customer)
An especially mean, dangerous, or malicious person. I wouldn't go messing with that dude—he's one ugly customer. There are some ugly customers in this part of town, so watch your back.
Farlex Dictionary of Idioms. © 2022 Farlex, Inc, all rights reserved.
An ill-natured or vicious individual, as in Watch out for Charlie when he's drinking; he can be an ugly customer. This phrase uses ugly in the sense of "mean" or "dangerous." [c. 1800]
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.