Learn English – Word to describe a very negative, pleasure-killing person

• She is "accommodating". She is eager to fit in with whatever you suggest. http://www.google.com/search?q=obliging&ie=UTF-8&oe=UTF-8&hl=en&client=safari#hl=en&q=accommodating

• She is "affable". That is, she tries to get along and not make a fuss over anything. Opposites might include "argumentative", "contrary", "difficult" (no matter what you suggest, she suggests something else, as if she were being opposite just to be opposite)

• She is "amenable". This is similar to "open"; she can accept any idea or plan. (often "open to _____" or "amenable to _____") http://www.google.com/search?q=obliging&ie=UTF-8&oe=UTF-8&hl=en&hl=en&q=amenable

• She is "complaisant" (not to be confused with "complacent") http://www.google.com/search?q=obliging&ie=UTF-8&oe=UTF-8&hl=en&hl=en&q=complaisant

• She is "deferential". That is, she accepts your wishes or judgment—to be polite (out of respect for you). Opposite might be "overbearing" (imposing her decision on you, regardless what you think.)

• She is "flexible". She can adapt to any situation. Perhaps she really doesn't care. Opposite is "rigid" (with very specific, unchangeable ideas of what she wants or would agree to)

• She is "obliging". That is, she wishes to please you by doing what you want to do. http://www.google.com/search?q=obliging&ie=UTF-8&oe=UTF-8&hl=en

• She is "pliant" (easily persuaded or influenced) http://i.word.com/idictionary/pliant

• She is "tractable" http://www.google.com/search?q=obliging&ie=UTF-8&oe=UTF-8&hl=en&hl=en&q=tractable

In the UK, posh is used primarily by working class people. It is used by aspirational ones in a positive way, "we got dressed up all posh, like", but it can also have a derogatory meaning. If you offered a napkin to a proud-to-be-working-class man, he might reply

Naa, I'm not posh, mate.

ladida is a mild expression of disapproval of somebody's affectations.

poncy is a working class way of saying "pretentious", and it's definitely derogatory. This might be used about the shirt:

You won't catch me wearing a poncy shirt like that!