玩意儿 is very colloquial (Beijing flavor). It can be neutral ('thing/gadget') or dismissive ('what kind of thing is this?!'). Tone of voice determines whether it's affectionate or contemptuous.
mistakes
The 意 is pronounced yì (4th tone) in isolation, but in 玩意儿 the whole word is often reduced to wányìr with a light, quick ending.
