not be someone's bag
be (not) (one's) bag
slang To be something that one is interested in or enjoys. Usually used in the negative. Dancing just isn't my bag—I always look really foolish. You can tell just by looking at her that fashion design is her bag.
See also: bag
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
not be someone's bagINFORMAL
If something is not your bag, you are not interested in it or are not good at it. They're a very successful band — they're just not my bag. `Being an umpire is not my bag,' says Anders. `I'd rather be a player.' Note: This expression may have originated in the slang spoken by American jazz musicians. They sometimes referred to the type of jazz they played, or to their own style of jazz, as their `bag'.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012