If it is a showbiz expression, remember in show business, it is bad luck to wish someone good luck. That is where the expression, "break a leg" comes from. So show business people will often reverse things to express a positive.
It does have the 'consumption' idea, but putting it out of its misery is undoubtedly a very positive thing to me- one beer's death is another person's joy. The song is a bit different, but I think that the beer example may hover in the middle.
On the subject of singing, another word that can have negative connotations is often used to express approval: She really nailed that top C.
Re: V to kill as a positive connotation? 
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