[1950s+] a sure bet.
SE in slang uses
[1940s+] (US milit.) any wound that guarantees the victim a passage out of a war zone and back to the USA.
[20C+] (orig. US) to feel excellent, very cheerful, extremely well, in the best of spirits; thus taste like a million v., to taste very good.
1. [1900s-10s] completely in love with.
2. [20C+] (Aus./N.Z.) in a hopeless state.
[20C+] to succeed absolutely, to do very well.
1. [1910s+] (US) to be extremely attractive; extremely smartly/fashionably dressed.
2. other than in dress, to look impressive, e.g. as a sporting performer.
[mid–late 19C] a phr. used of a very sure bet.