While 'being ugly' is a common phrasing, there are other variants, like 'acting ugly', 'are/were ugly', and so on.
"I can be a really ugly guy when I go without smoke break, man."
"Sorry about my mom acting so ugly to you during dad's funeral."
"S'alright. I acted pretty ugly to him while he was alive, so I understand why she'd do the same to me while she was grieving."