This discussion gives me the opportunity to link to a Youtube video of Ismo Leikola performing on Conan's late night show. The bit is titled "Ass is the most complicated word in the English Language".
Ismo Leikola is a fellow Finn, and once voted as the World's Funniest Person.
When you hear slang, idioms or phrases you can´t understand try to think about the context they were being used in and that will often help you work out the meaning. So in this case you know they were talking about a car. One guy may have said to the other something like. That is one ugly assed car. The person who was saying it may have been shaking his head at the time, showing disapproval, or you might have seen from the look on his face that he didn´t like it. Look for these cues, body language, and the context when trying to work out what we mean:) Even Native English speakers have to do this as we make up new idioms, slang and phrasal verbs all the time:)
Timo, I opened the discussion after I read the title only to add Ismo Leikola's video,
just to see that you have added it before me. It's sooooo funny and first time I
watched it several months ago, I really laughed at the top of my voice :D hehe