"Holy cow!" (2,2)
(Other definitions for yikes that I've seen before include "alarmed expression" , "Expression of alarm or astonishment" , "Watch out" , "Exclamation of surprise or alarm" , "Gosh! - Oh no!" .)
(Other definitions for egad that I've seen before include "Old oath" , "Oath sworn" , "Old exclamation; aged (anagram)" , "Forgotten curse" , "Archaic exclamation of surprise" .)