From Longman Dictionary of Contemporary Englishknock/blow somebody’s socks offknock/blow somebody’s socks offinformalSURPRISED to surprise and excite someone very much a new band that will knock your socks off → sock
Examples from the Corpus
knock/blow somebody’s socks off• This in-your-face marketing could be forgiven if the food absolutely knocked your socks off.• The current crop of non-Windows databases can knock the socks off their predecessors.• And yet the correlations just knock my socks off..• So, he popped down to my office, stuck this demo on the turntable and it just blew my socks off. 