A euphemism for wiseass, smartass, cracking wise.
Frank Sinatra was prone to use this on stage at The Sands during the Summit Meeting the Rat Pack had there in 1961. When he did, he was usually referring to Sammy Davis, Jr..
Frank: Sammy, what the... why aren't you wearing your nice dinner jacket like the rest of us?
Sammy: Well gee Frank! You know what happens when I wear all black!
Frank: Don't be a wiseacre!