put sth down to experience	if sth bad happened but you decided to learn from it instead of being upset by it
to know where you stand	if you don't know what your position is or what your situation is and you are worried about it
give me food for thought	sth that makes you think a lot about it
learn my lesson	if sth bad happens to you and you decide that it will never happen again
teach him a lesson	dać nauczkę
got the message	someone become aware of sth
see/put the record straight	wyprostować cos, powiedziec jak jest naprawdę
hear sth on/through the grapevine	heard sth from someone who heard it from someone else
figment of your imagination	sth which is not true
lose sight of	forgotten a central truth about sth
have second thoughts about	decided sth but now not sure about it
the ins and outs of	the details of
what beats me	what I cannot understand