Yeah, I'm with Aus on this one for the same reason, it was somewhat devoid of anything that even resembles a joke, really just a random snipped of normal conversation. That happens to me a lot, you know you've got a great setup, and you can feel the punchline somewhere in the back of your mind but can't quite come up with something.
My advice though is to write down your setup and come back to it later, cos a setup will often prompt you to think of a punchline when you next see it.
For this I'd have come back and gone with something like:
Chuck: Wow, that's an awesome blue tie! Have you got any more?
Chen: No, just the one.
Chuck: Oh. What about a blue synthetic vagina with detachable vibrating anal beads?
Chen: No, only in green or yellow.
Chuck: Damn.
Chen: I know!
Feel free to george* that in too, or re-write it if it sparks another idea :)
Alternately if you were trying to imply that this occurred in a retail store and Chen's the salesman, you'd have been better using the clothing store background, as that one's a basement storage locker with random crap and clutter all over the shelves (that I just couldn't be arsed drawing in at the time).
*george ; verb ; to retroactively edit established media, more often than not detracting from the quality of the original by replacing guns with walkie-talkies and shit.