Reminds me of a coworker that asked me to pick up a shot glass in Beijing at Planet Hollywood as he collected them. I thought the whole purpose was to collect them where you go, not have someone get one for you so you can look like you went there.

Does your friend never fly UA international? I don't buy Duty Free so don't know what the bags look like, Are they UA specific?

But to answer your question, can't hurt to ask. But be prepared to pay for it (just kidding)(maybe).