From Longman Dictionary of Contemporary Englishknock somebody’s socks offknock somebody’s socks off (also knock somebody dead) spokenSURPRISEDHAPPY to surprise and please someone by being very impressive With that dress, you’ll knock him dead. → knock
Examples from the Corpus
knock somebody’s socks off• Cierra's performance knocked my socks off!• And yet the correlations just knock my 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. 