Scarlett's a Flop

While getting my usual dose of trashy celebrity news a few days ago, I came across an article about Scarlett Johansson and her problems with sweating:

http://www.theage.com.au/lifestyle/people/scarlett-johanssons-sweaty-problem-20100506-ubek.html

Rather than muse over why I find it necessary to waste my time reading about the bodily functions of people I don't know, I want to look at something in particular Johansson was quoted as saying in the article

"I like the getting ready part. I like the hair and the make-up and the pretty dress... It's just getting on the red carpet I just instantly flop sweat."

What the heck is "flop sweat"? It's certainly a phrase I've never heard before. For once the Oxford English Dictionary wasn't able to come to my rescue - It had no information on the phrase. Webster's online was much more helpful, unsurprising perhaps, given it was used by an American - it appears that only Americans "flop sweat" ( http://www.merriam-webster.com/dictionary/flop+sweat ). I was somewhat surprised to see that it's earliest cited reference was in 1953. Clearly Americans have been suffering this problem without telling us for a while.

Webster's tells us that this phrase acts as a noun in English, but I'm pretty unconvinced by that. Given the context above, it's very much functioning as a verb - there's no other verb in " I just instantly flop sweat" and it's being modified by the adverb "instantly" - nouns modified by adverbs don't really happen in English.

Even though it's clearly not a noun, but some kind of verb, as an Australian English speaker I find it difficult to parse. I'm not very sure which part is the core verb of the construction, which is made rather difficult by the fact that both "flop" and "sweat" can be either nouns or verbs. Option a) is that "flop" is the verb, and matches with things like "I drip sweat" and "I shed skin". Option b) is that it is "sweat" that is the verb and "flop" is a modifier, like "heat sweat" and "stress eat".

If we were to turn it into a progressive aspect (that's basically an -ing form in English) then we would have to place the progressive suffix on the verb of the sentence:

Option a) "I was flopping sweat"
Option b) "I was flop sweating"

I thought that option a) was more likely before I did this test, but perhaps it is "sweat" that is the verbal element here. I'm still confused. If anyone else has heard this phrase before, or has any thoughts on it I'd love to hear.