Word Request – How to Describe a Nut That Does Not Tighten

• 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

That kid is 'swaying' from side to side as he sings.

sway - Move or cause to move slowly or rhythmically backward and forward or from side to side

Another possibility is to rock, which one can do with either his body or his head:

rock - Move gently to and fro or from side to side