" Sniff test "
Sniff an item of clothing (or food) to check if it might be suitable to wear (or eat).
I've worn that shirt before but when I gave the underarms the sniff test I thought I'd be okay to wear it again.
Where did it originate?:
Late 20th century.
Where is it used?:
Mostly Britain, but becoming more common elsewhere.
Hear the idiom spoken: