So how do you gift a coupon?

You can't. But you could give it away in a thread or something.

EDIT: Never mind, thought you were asking how to give it away on sg.

this

Isn't this guy asking how to gift coupons in general? Not asking how to do it on this site? At least that's how I read it..

invite someone to trade and then select it

Buy game using coupon, trade game for stuff.

You gift it via the trade interface.

The method of giving it to someone isn't important. I'm simply trying to figure out any way to do it. Even if I gave it to someone here, it's still located on Steam.

Several of you mentioned a trade option. I was unaware of such a feature existing on Steam, but will look for it. The only thing I'd known of, and have used before, was the "Send gift" button within the Inventory, but it's not available for this item.

Edit: Thanks for the tip. I now see the "invite to trade" option. I've never done any trading on Steam before, so didn't know that even existed. I hardly ever use the Friends menu, and even then it's usually just a double click to bring up the chat window --wasn't aware of all the right-click stuff in there. :)