Her: Maybe this?
You: Ugh. No way. I'd look WAY too fat
If it is a girl working at the place...
Don't keep up that dialogue just because you got a smile. It was WAY out of context and she knew your intention..so justify it...
Her: giggles (action, not word)
You: Your welcome. Must be a bore working when it's quiet so I thought i'd come brighten your day up...
Now...take her into another world apart from work. If she brings up work, ask her what her dream job would be, and tell her about yours....or tell her how everybody always hates one person they work with- and tell her to secretly point to who it is she hates, and then its your little secret etc.
Keep it short.
If it is another customer browsing around shopping...
same reply, same principle applies- she knows why you did it.
But this time follow up with:
You: I couldn't help myself. Girls are designed for shopping. You know us guys we get bored SO easily with this...
She will be curious and probably feed into what you are shopping for...
Now you have a conversation going....
Fun opener by the way!! ...Although stay away from lingerie sections.