I found this on SO and googled the idiom "suit yourself", but I couldn't find a matching translation. The context was that the questioner was nitpicking and the answerer lost his patience.
"Suit yourself" means, basically, "ok, do whatever you want; I'm done arguing". It implies that the speaker made some attempt (perhaps small) to get the listener to do something; it's not generally something you say out of the blue. It's a pretty common idiom in US English. I don't know the derivation.
Cambridge Advanced Learner's Dictionary gives the definition of "suit yourself" as follows:
an expression used either humorously or angrily to mean 'do what you want to do'
There is a nice discussion here as well. I'm copying that post below in case link rot can happen.
Posted by R. Berg on May 22, 2004
In Reply to: Re: But why else posted by Word Camel on May 21, 2004
: : would it be said then? It is a context of 'if you don't won't to go my way or their way, then I guess you can go your own way'.
: : ""Suit yourself" doesn't always have a context of argument or conflict, any more than "Do what you want" does. It can be said neutrally. One has to listen for the tone."
: : I don't think this is suitable to be used in agreement. By all means, listen to the tone.
: : "Hey, we're all going to the game. Want to come?"
: : "Sure great." "Suit yourself"
: : or "Would you like more steak?" Yummy "Suit yourself"
: : how about "I would rather date Mary than Beth." Me too, I think Mary is prettier. "Suit yourself"
: : "Suit yourself doesn't work in any of these examples - as given. Switch the response to one that disagrees and "suit yourself" works in each example.
: Not so. Yes, it's probably more common these days to hear it used facetiously but there are plenty of instances in which it is used neutrally.
: "We have swordfish or steak, so suit yourself!" "There are three bedrooms available in the cabin so you can suit yourself."
I don't understand "Suit yourself" as having to do mainly with situations of agreement or disagreement. It's said when offering someone a choice or clarifying that the choice belongs to that person, not to oneself. It's a lot like "Up to you" and not a lot like "Up yours."
In English, one of the meanings of the verb "to suit" is to be pleased with, or to find suitable. So, for example, if you are trying to fit an appointment into someone's schedule, you might say:
I'm free on Thursday at 1:00. Does that suit you?
You are asking whether it is agreeable to the other person to meet on Thursday at 1:00. If you reach an agreement, you might say:
That suits me fine.
When you say:
you are using "suit" in this sense. The normal context is that the speaker is frustrated because he or she has been trying to accommodate both sides, but the other person is not being cooperative. It's roughly equivalent to saying:
Fine; do whatever you want to do, then.
It has the implication that the speaker is giving up or doesn't care; you would be more likely to hear it at the end of a conversation than in the middle.
Considering what it literally is saying - "suit yourself" - the figurative meaning seems to derive from the act of donning a suit of armor or cloths without the assistance of the speaker. According to Etymonline, verb forms of "suit" go back to the 15th century meaning make agreeable. So "go ahead, agree with yourself (and not me)" seems to be the underlying context when intoned with some kind of exasperation. This seems to lend itself to the more graphic phrase "you can go fuck yourself". I think that "suit yourself" can be polite way of expressing a disagreement or a difference of opinion that one has no serious stake in arguing, but which one wants to call to attention. To call it "neutral" though seems a bit off.