Ad for Chex Mix: “a bag of interesting”. The phrase is even trademarked.
This is an adjective zero-converted into a mass noun — an instance of a larger pattern that Neal Whitman (summarizing earlier discussion) posted about a while back, under the heading “Buckets, Boxes, and Bags”, about
bucket/box/bag of awesome [Adj] / fail [V]
and related expressions conveying high degree (of awesomeness and failing, in these examples; of interestingness, in the Chex Mix case).
The ‘large amount’ or ‘high degree’ component of meaning is contributed by the head noun — bucket, box, or bag in these examples, but others are attested (see the comments on Neal’s posting): bowl, bottle, world, shipment, etc. (often modified by high-amount adjectives like big or giant). The converted words are affectively marked, as positive (interesting, awesome) or negative (fail as above, awful in the following example).
Steve Jobs would call this a bag of awful.
(an allusion to Jobs saying that Blu-Ray is “a bag of hurt”).
A few more words about extended senses of bag, in addition to uses with nounings. There are uses with ordinary partitive complements (of + NP), to sum up a state (cf. bundle):
Jethro had turned into a bag of bad temper. He would be eight next week and his big brother had promised to take him deep sea fishing when he was that old. Now Thomas said he was too small to go! (link)
Apparently she freaked the mediums out and some of them actually demanded she leave. One relayed the message that “she was a bag of bad energy,” and that her aura was telling the spirits to “back off.” (link)
And ‘large amount’ uses with partitives, similar to such uses of bunch, pile, and the like:
At least your wife will have something to show for shopping. She will NOT be acquiring a bag of bad habits, at the end of your bad dream vacation. But you will [in playing golf], I guarantee it. (link)
Finally, there’s an insult that was new to me (and to comedian Louis CK, who riffs on it in this video): “Suck a bag of dicks!” (conveying, roughly, ‘Fuck you!’).
(None of these uses of bag made it into OED2.)

