I'm looking for a good English slang for someone who gives opinions — usually negative — without being asked for them.
Are there any? I know in Hungarian they are called megmondóember but I can't find any good word for them in English.
In British English you might use:
know-it-all - someone who behaves as if they have all the answers to something, and know more than everybody else, usually giving these answers without being asked.
busybody - from the two words busy meaning engaged in an activity and body meaning person - somebody who interferes in others' affairs.
nosy parker - slightly archaic, nosy meaning interested in things which do not concern them, and Parker being a proper noun.
There aren't actually many precise words for this, but people that do it are said to butt in or mouth off.
Noun: kibitzer ki-bit-su(r)
(Yiddish) a meddler who offers unwanted advice to others
Derived forms: kibitzers
Type of: meddler
And the verb is kibitz:
Verb: kibitz ki-bits
Make unwanted and intrusive comments
"Don't kibitz: he's sensitive";
Derived forms: kibitzed, kibitzing, kibitzes
Type of: comment, notice, point out, remark
buttinsky or buttinski, according to Merriam-Webster:
a person given to butting in --- a troublesome meddler.
Example of buttinsky in a sentence: there's always some buttinsky who has to tell you there's a better way to do whatever you're doing.
Although the word originated in the US, here are several examples from the OED of use by British writers:
1933 D. L. Sayers Murder must Advertise iv. 69, I never..met with such a bunch of buttinskis... Nothing is sacred to you.
1960 P. G. Wodehouse Jeeves in Offing v. 50 It is never pleasant for a man of sensibility to find himself regarded as a buttinski and a trailing arbutus
For origin, the OED says:
Etymology: Jocular, < butt in (see butt v.1 1d) + -sky, final element in many Slavonic names
butt in, OED
to butt in: to thrust oneself unceremoniously and uninvited into an affair, discussion, etc.; to intrude, interfere without good reason. orig. U.S.