Someone Who Is So Ugly It hurts Your Eyes To Look at Them Or So Ugly You Find The Nearest Sharp Object And Stab Yourself And The Ugly Mut.
ugly hurting eyes mut
Joe: Damn, Shes Ugly As Fuck, How Are You Still looking At Her?
Bruce: *searching for sharp object*
When something is so ugly that when you see it, it actively makes you mutter "Fuck." due to the enormous amount of stress caused by knowing it's horrid existence and the fact that people will meet this thing. "Fuck" is also muttered for the creator as an obligation since the creator clearly should've realized he/she has fucked up while making it and stopped making it.
Oliver: Hey Jacob have you seen Sonic in the new movie?
Jacob: No. Why?
Oliver: I'm telling you Sonic is Fuck Ugly dude.